Antihistamine (Oral route, parenteral route, rectal route)

Brand Names:

AHIST
Alavert
Allegra
Aller-Chlor
Aller-G-Time
Antivert
Atarax
Benadryl
Brovex
Children's Benadryl Allergy Fastmelt
Children's Pedia Care
Clarinex
Complete Allergy
Compoz Nighttime Sleep Aid
Diphen
Dormin Sleep Aid
Dramamine
Dytan
Dytuss
FusePaq Dicopanol
Histex PD
Hydramine
Lodrane
Nolahist
Optimine
Pediatex 12
Periactin
Polaramine
Q-dryl
Quenalin
Serabrina LA France
Siladryl
Silphen
Simply Allergy
Simply Sleep
Sleep-Ettes D
Sleep Formula
Sleepinal
Sominex
Tavist
Twilite
Unisom
Unisom Sleepgels Maximum Strength
Vistaril
Xyzal
Zymine
ZyrTEC
Allergy Formula
Allergy Formula Liquid
Basic Care Allergy Relief Caplets
Benadryl Allergy Children's
Benadryl Children's
Buckley's Jack & Jill Bedtime
Clear Allergy Formula For Adults And Children
Diphedryl Clear
Equate Nighttime Sleep Aid Liquid - Berry Flavour
Exact Allergy Formula Caplets
Exact Nighttime Sleep-Aid - Berry
Gravol

Dosage Forms:

Solution
Tablet
Syrup
Tablet, Extended Release
Suspension, Extended Release
Tablet, Chewable
Capsule
Liquid
Tablet, Disintegrating
Elixir
Suspension
Capsule, Liquid Filled
Suppository

Uses of This Medicine:

Antihistamines are used to relieve or prevent the symptoms of hay fever and other types of allergy. They work by preventing the effects of a substance called histamine, which is produced by the body. Histamine can cause itching, sneezing, runny nose, and watery eyes. Also, in some persons histamine can close up the bronchial tubes (air passages of the lungs) and make breathing difficult.

Some of the antihistamines are also used to prevent motion sickness, nausea, vomiting, and dizziness. In patients with Parkinson's disease, diphenhydramine may be used to decrease stiffness and tremors. Also, the syrup form of diphenhydramine is used to relieve the cough due to colds or hay fever. In addition, since antihistamines may cause drowsiness as a side effect, some of them may be used to help people go to sleep.

Hydroxyzine is used in the treatment of nervous and emotional conditions to help control anxiety. It can also be used to help control anxiety and produce sleep before surgery.

Some antihistamines are used in the treatment of chronic urticaria, which is a persistent hive-like rash.

Antihistamines may also be used for other conditions as determined by your doctor.

Antihistamine preparations are available both over-the-counter (OTC) and with your doctor's prescription.

Do not give any over-the-counter (OTC) cough and cold medicine to a baby or child under 4 years of age. Using these medicines in very young children might cause serious or possibly life-threatening side effects .

Make certain your health care professional knows if you are on a low-sodium, low-sugar, or any other special diet. Most medicines contain more than their active ingredient, and many liquid medicines contain alcohol.

Before Using This Medicine:

Allergies—

Tell your doctor if you have ever had any unusual or allergic reaction to medicines in this group or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Children—

Serious side effects, such as convulsions (seizures), are more likely to occur in younger patients and would be of greater risk to infants than to older children or adults. In general, children are more sensitive to the effects of antihistamines. Also, nightmares or unusual excitement, nervousness, restlessness, or irritability may be more likely to occur in children.

Older adults—

Elderly patients are usually more sensitive to the effects of antihistamines. Confusion; difficult or painful urination; dizziness; drowsiness; feeling faint; or dryness of mouth, nose, or throat may be more likely to occur in elderly patients. Also, nightmares or unusual excitement, nervousness, restlessness, or irritability may be more likely to occur in elderly patients.

Pregnancy—

Hydroxyzine is not recommended for use in the first months of pregnancy since it has been shown to cause birth defects in animal studies when given in doses many times higher than the usual human dose. Be sure you have discussed this with your doctor.

Desloratadine and fexofenadine have not been studied in pregnant women. However, studies in animals have shown that these medicines cause birth defects or other problems when given in doses higher than the usual human dose. Before taking this medicine, make sure your doctor knows if you are pregnant or if you may become pregnant.

Azatadine, brompheniramine, cetirizine, chlorpheniramine, clemastine, cyproheptadine, dexchlorpheniramine, dimenhydrinate, diphenhydramine, doxylamine, and loratadine have not been studied in pregnant women. However, these medicines have not been shown to cause birth defects or other problems in animal studies.

Breast-feeding—

Small amounts of antihistamines pass into the breast milk. Use is not recommended since babies are more susceptible to the side effects of antihistamines, such as unusual excitement or irritability. Also, since these medicines tend to decrease the secretions of the body, it is possible that the flow of breast milk may be reduced in some patients. It is not known yet whether cetirizine, desloratadine, or loratadine cause these same side effects.

Other medicines—

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking any of these medicines, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using medicines in this class with any of the following medicines is not recommended. Your doctor may decide not to treat you with a medication in this class or change some of the other medicines you take.

Alfuzosin
Amiodarone
Amisulpride
Amitriptyline
Amprenavir
Anagrelide
Apomorphine
Aripiprazole
Aripiprazole Lauroxil
Arsenic Trioxide
Artemether
Asenapine
Astemizole
Atazanavir
Azithromycin
Bedaquiline
Bepridil
Brofaromine
Bromopride
Buprenorphine
Buserelin
Calcium Oxybate
Ceritinib
Chloroquine
Chlorpromazine
Ciprofloxacin
Cisapride
Citalopram
Clarithromycin
Clofazimine
Clomipramine
Clorgyline
Clothiapine
Clozapine
Crizotinib
Cyclobenzaprine
Dabrafenib
Darunavir
Dasatinib
Degarelix
Delamanid
Delavirdine
Desipramine
Deslorelin
Deutetrabenazine
Dexmedetomidine
Disopyramide
Dofetilide
Dolasetron
Domperidone
Donepezil
Doxepin
Dronedarone
Droperidol
Ebastine
Efavirenz
Encorafenib
Entrectinib
Eribulin
Erythromycin
Escitalopram
Famotidine
Felbamate
Fexinidazole
Fingolimod
Flecainide
Fluconazole
Fluoxetine
Fluvoxamine
Formoterol
Foscarnet
Fosphenytoin
Fostemsavir
Furazolidone
Galantamine
Gatifloxacin
Gemifloxacin
Gepirone
Glasdegib
Gonadorelin
Goserelin
Granisetron
Grepafloxacin
Halofantrine
Haloperidol
Histrelin
Hydroquinidine
Hydroxychloroquine
Hydroxyzine
Ibutilide
Iloperidone
Imipramine
Indinavir
Inotuzumab Ozogamicin
Iproniazid
Isocarboxazid
Itraconazole
Ivabradine
Ivosidenib
Ketoconazole
Lapatinib
Lazabemide
Lenvatinib
Leuprolide
Levofloxacin
Levoketoconazole
Levomethadyl
Linezolid
Lofexidine
Lopinavir
Lumefantrine
Macimorelin
Magnesium Oxybate
Mefloquine
Mesoridazine
Methadone
Methotrimeprazine
Methylene Blue
Metronidazole
Mibefradil
Mifepristone
Mirtazapine
Mizolastine
Mobocertinib
Moclobemide
Moricizine
Moxifloxacin
Nafarelin
Nefazodone
Nelfinavir
Nialamide
Nilotinib
Norfloxacin
Octreotide
Ofloxacin
Olanzapine
Ondansetron
Osilodrostat
Osimertinib
Oxaliplatin
Pacritinib
Paliperidone
Panobinostat
Papaverine
Pargyline
Paroxetine
Pasireotide
Pazopanib
Pentamidine
Perphenazine
Phenelzine
Pimavanserin
Pimozide
Pipamperone
Piperaquine
Pitolisant
Ponesimod
Posaconazole
Potassium Citrate
Potassium Oxybate
Probucol
Procainamide
Procarbazine
Prochlorperazine
Promethazine
Propafenone
Protriptyline
Quetiapine
Quinidine
Quinine
Ranolazine
Rasagiline
Relugolix
Ribociclib
Risperidone
Ritonavir
Safinamide
Saquinavir
Selegiline
Selpercatinib
Sertindole
Sertraline
Sevoflurane
Sodium Oxybate
Sodium Phosphate
Sodium Phosphate, Dibasic
Sodium Phosphate, Monobasic
Solifenacin
Sorafenib
Sotalol
Sparfloxacin
Sulpiride
Sultopride
Sunitinib
Tacrolimus
Tamoxifen
Telaprevir
Telavancin
Telithromycin
Terfenadine
Tetrabenazine
Thioridazine
Tipranavir
Toloxatone
Tolterodine
Toremifene
Tranylcypromine
Trazodone
Triclabendazole
Trimipramine
Triptorelin
Troleandomycin
Vandetanib
Vardenafil
Vemurafenib
Venlafaxine
Vilanterol
Vinflunine
Voclosporin
Voriconazole
Vorinostat
Ziprasidone
Zolmitriptan
Zotepine

Using medicines in this class with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Abiraterone Acetate
Acecainide
Acepromazine
Adagrasib
Adenosine
Ajmaline
Alefacept
Alfentanil
Alfuzosin
Almotriptan
Alprazolam
Amantadine
Amifampridine
Amiodarone
Amisulpride
Amitriptyline
Amobarbital
Amoxapine
Amphetamine
Anagrelide
Anileridine
Apomorphine
Aprindine
Aripiprazole
Aripiprazole Lauroxil
Arsenic Trioxide
Artemether
Asenapine
Astemizole
Atazanavir
Azimilide
Azithromycin
Baclofen
Bedaquiline
Benperidol
Benzhydrocodone
Benzphetamine
Bretylium
Bromazepam
Bromopride
Buprenorphine
Bupropion
Buserelin
Buspirone
Butabarbital
Butorphanol
Calcium Oxybate
Cannabidiol
Cannabis
Capmatinib
Carbamazepine
Carbinoxamine
Carisoprodol
Carphenazine
Ceritinib
Cetirizine
Chloral Hydrate
Chlordiazepoxide
Chloroquine
Chlorpromazine
Chlorzoxazone
Ciprofloxacin
Citalopram
Clarithromycin
Clobazam
Clofazimine
Clomipramine
Clonazepam
Clorazepate
Clothiapine
Clozapine
Codeine
Crizotinib
Cyclobenzaprine
Dabrafenib
Dalfopristin
Dantrolene
Daridorexant
Dasatinib
Degarelix
Delamanid
Desipramine
Deslorelin
Desvenlafaxine
Deutetrabenazine
Dexmedetomidine
Dextroamphetamine
Dextromethorphan
Diacetylmorphine
Diazepam
Dibenzepin
Dichloralphenazone
Difenoxin
Digoxin
Dihydrocodeine
Diphenhydramine
Diphenoxylate
Disopyramide
Dofetilide
Dolasetron
Domperidone
Donepezil
Doxepin
Doxylamine
Droperidol
Duloxetine
Ebastine
Efavirenz
Encainide
Encorafenib
Enflurane
Entrectinib
Epinephrine
Eribulin
Erythromycin
Escitalopram
Esketamine
Estazolam
Eszopiclone
Ethchlorvynol
Ethopropazine
Ethylmorphine
Famotidine
Fedratinib
Felbamate
Fenfluramine
Fentanyl
Fexinidazole
Fingolimod
Flecainide
Flibanserin
Fluconazole
Flunitrazepam
Fluoxetine
Fluphenazine
Flurazepam
Fluspirilene
Fluvoxamine
Formoterol
Foscarnet
Fosphenytoin
Fospropofol
Fostemsavir
Gabapentin
Gabapentin Enacarbil
Galantamine
Gatifloxacin
Gemifloxacin
Gepirone
Glasdegib
Glucagon
Glycopyrrolate
Glycopyrronium Tosylate
Gonadorelin
Goserelin
Granisetron
Halazepam
Halofantrine
Haloperidol
Halothane
Hexobarbital
Histrelin
Hydrocodone
Hydromorphone
Hydroquinidine
Hydroxyamphetamine
Hydroxychloroquine
Hydroxytryptophan
Hydroxyzine
Ibutilide
Iloperidone
Imipramine
Inotuzumab Ozogamicin
Isoflurane
Isradipine
Itraconazole
Ivabradine
Ivosidenib
Josamycin
Ketamine
Ketazolam
Ketobemidone
Ketoconazole
Lacosamide
Lapatinib
Lasmiditan
Lefamulin
Lemborexant
Lenvatinib
Leuprolide
Levocetirizine
Levofloxacin
Levoketoconazole
Levomilnacipran
Levorphanol
Lidoflazine
Linezolid
Lisdexamfetamine
Lithium
Lofexidine
Lopinavir
Lorazepam
Lorcainide
Lorcaserin
Loxapine
Lumefantrine
Macimorelin
Magnesium Oxybate
Mavacamten
Meclizine
Mefloquine
Melperone
Meperidine
Mephobarbital
Meprobamate
Meptazinol
Mesoridazine
Metaxalone
Methacholine
Methadone
Methamphetamine
Methdilazine
Methocarbamol
Methohexital
Methotrexate
Methotrimeprazine
Methylene Blue
Metoclopramide
Metrizamide
Metronidazole
Midazolam
Mifepristone
Milnacipran
Mirtazapine
Mizolastine
Mobocertinib
Molindone
Moricizine
Morphine
Morphine Sulfate Liposome
Moxifloxacin
Nafarelin
Nalbuphine
Nelfinavir
Nicomorphine
Nilotinib
Nitrazepam
Nitrous Oxide
Norfloxacin
Nortriptyline
Octreotide
Ofloxacin
Olanzapine
Ondansetron
Opium
Opium Alkaloids
Orphenadrine
Osilodrostat
Osimertinib
Oxaliplatin
Oxazepam
Oxycodone
Oxymorphone
Ozanimod
Pacritinib
Paliperidone
Palonosetron
Panobinostat
Papaveretum
Papaverine
Paregoric
Paroxetine
Pasireotide
Pazopanib
Pentamidine
Pentazocine
Pentobarbital
Perampanel
Perazine
Periciazine
Perphenazine
Phenobarbital
Phenytoin
Pimavanserin
Pimozide
Pipamperone
Piperacetazine
Pipotiazine
Piritramide
Pirmenol
Pitolisant
Ponesimod
Porfimer
Posaconazole
Potassium Oxybate
Prajmaline
Prazepam
Pregabalin
Primidone
Probucol
Procainamide
Procarbazine
Prochlorperazine
Promazine
Promethazine
Propafenone
Propofol
Propoxyphene
Protriptyline
Quazepam
Quetiapine
Quinidine
Quinine
Quinupristin
Quizartinib
Ramelteon
Ranolazine
Regadenoson
Relugolix
Remifentanil
Remimazolam
Remoxipride
Revefenacin
Ribociclib
Risperidone
Ritlecitinib
Ritonavir
Ropeginterferon Alfa-2b-njft
Roxithromycin
Scopolamine
Secobarbital
Secretin Human
Selpercatinib
Sematilide
Sertindole
Sertraline
Sevoflurane
Simeprevir
Siponimod
Sodium Oxybate
Sodium Phosphate
Sodium Phosphate, Dibasic
Sodium Phosphate, Monobasic
Solifenacin
Sorafenib
Sotalol
Spiramycin
Sufentanil
Sulfamethoxazole
Sulpiride
Sultopride
Sunitinib
Suvorexant
Tacrolimus
Tamoxifen
Tapentadol
Tedisamil
Telaprevir
Telavancin
Telithromycin
Temazepam
Tetrabenazine
Thiethylperazine
Thiopental
Thiopropazate
Thioridazine
Tilidine
Tiotropium
Tizanidine
Tocilizumab
Tolonium Chloride
Tolterodine
Topiramate
Toremifene
Tramadol
Trazodone
Triazolam
Triclabendazole
Trifluoperazine
Trifluperidol
Triflupromazine
Trimeprazine
Trimethoprim
Trimipramine
Triptorelin
Vandetanib
Vardenafil
Vemurafenib
Venetoclax
Venlafaxine
Vilanterol
Vilazodone
Vinflunine
Voclosporin
Voriconazole
Vorinostat
Vortioxetine
Zaleplon
Zileuton
Ziprasidone
Zolpidem
Zopiclone
Zotepine
Zuclopenthixol
Zuranolone

Other interactions—

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Using medicines in this class with any of the following is usually not recommended, but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use your medicine, or give you special instructions about the use of food, alcohol, or tobacco.

Ethanol
Grapefruit Juice

Other medical problems—

The presence of other medical problems may affect the use of medicines in this class. Make sure you tell your doctor if you have any other medical problems, especially:

Enlarged prostate or
Urinary tract blockage or difficult urination—Antihistamines may make urinary problems worse.

Glaucoma—These medicines may cause a slight increase in inner eye pressure that may make the condition worse.

Intestinal obstruction or
Stomach ulcer—Use of cyproheptadine may make these conditions worse.

Liver disease or
Kidney disease—Effects of desloratadine may be increased because of slower removal from the body.

Proper Use of This Medicine:

For patients taking this medicine by mouth:

Antihistamines can be taken with food or a glass of water or milk to lessen stomach irritation if necessary.
If you are taking the extended-release tablet form of this medicine, swallow the tablets whole. Do not break, crush, or chew before swallowing.

For patients taking dimenhydrinate or diphenhydramine for motion sickness:

Take this medicine at least 30 minutes or, even better, 1 to 2 hours before you begin to travel.

For patients using the suppository form of this medicine:

To insert suppository: First remove the foil wrapper and moisten the suppository with cold water. Lie down on your side and use your finger to push the suppository well up into the rectum. If the suppository is too soft to insert, chill the suppository in the refrigerator for 30 minutes or run cold water over it before removing the foil wrapper.

For patients using the injection form of this medicine:

If you will be giving yourself the injection, make sure you understand exactly how to give it. If you have any questions about this, check with your health care professional.

Antihistamines are used to relieve or prevent the symptoms of your medical problem. Take them only as directed. Do not take more of them and do not take them more often than recommended on the label, unless otherwise directed by your doctor. To do so may increase the chance of side effects.

Dosing—

The dose medicines in this class will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of these medicines. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

For use as an antihistamine:

For oral dosage form (tablets):
- Adults—1 to 2 milligrams (mg) every eight to twelve hours as needed.
- Children 12 years of age and older—0.5 mg to 1 mg two times a day as needed.
- Children 4 to 12 years of age—Use and dose must be determined by your doctor.
- Children and infants up to 4 years of age—Use is not recommended .

For regular (short-acting) oral dosage forms (capsules, tablets, or liquid):
- Adults and teenagers—4 milligrams (mg) every four to six hours as needed.
- Children 6 to 12 years of age—2 mg every four to six hours as needed.
- Children 4 to 6 years of age—1 mg every four to six hours as needed.
- Children and infants up to 4 years of age—Use is not recommended .
For injection dosage form:
- Adults and teenagers—10 milligrams (mg) injected into a muscle, under the skin, or into a vein every eight to twelve hours.
- Children 4 to 12 years of age—0.125 mg per kilogram (0.06 mg per pound) of body weight injected into a muscle, under the skin, or into a vein three or four times a day as needed.
- Children and infants up to 4 years of age—Use is not recommended .

For oral dosage forms (syrup and tablets):
- Adults—5 to 10 milligrams (mg) once a day.
- Children 6 years of age and older—5 to 10 mg once a day.
- Children 4 to 6 years of age—2.5 mg once a day, up to a maximum of 5 mg once a day or 2.5 mg twice a day.
- Children and infants up to 4 years of age—Use is not recommended .

For regular (short-acting) oral dosage forms (tablets or liquid):
- Adults and teenagers—4 milligrams (mg) every four to six hours as needed.
- Children 6 to 12 years of age—2 mg three or four times a day as needed.
- Children 4 to 6 years of age—Use and dose must be determined by your doctor.
- Children and infants up to 4 years of age—Use is not recommended .
For long-acting oral dosage forms (capsules or tablets):
- Adults—8 or 12 milligrams (mg) every eight to twelve hours as needed.
- Children 12 years of age and older—8 mg every twelve hours as needed.
- Children 4 to 12 years of age—Use and dose must be determined by your doctor.
- Children and infants up to 4 years of age—Use is not recommended .
For injection dosage form:
- Adults—5 to 40 milligrams (mg) injected into a muscle, into a vein, or under the skin.
- Children 4 years of age and older—0.0875 mg per kilogram (0.04 mg per pound) of body weight injected under the skin every six hours as needed.
- Children and infants up to 4 years of age—Use is not recommended .

For oral dosage forms (tablets or liquid):
- Adults and teenagers—1.34 milligrams (mg) two times a day or 2.68 mg one to three times a day as needed.
- Children 6 to 12 years of age—0.67 to 1.34 mg two times a day.
- Children 4 to 6 years of age—Use and dose must be determined by your doctor.
- Children and infants up to 4 years of age—Use is not recommended .

For oral dosage forms (tablets or liquid):
- Adults and children 14 years of age and older—4 milligrams (mg) every eight hours. The doctor may increase the dose if needed.
- Children 6 to 14 years of age—4 mg every eight to twelve hours as needed
- Children 4 to 6 years of age—2 mg every eight to twelve hours as needed
- Children and infants up to 4 years of age—Use is not recommended .

For oral dosage form (tablets):
- Adults and children 12 years of age and older—5 milligrams (mg) once a day.
- Children 4 to 12 years of age—Use and dose must be determined by your doctor.
- Children and infants up to 4 years of age—Use is not recommended .

For regular (short-acting) oral dosage form (tablets or liquid):
- Adults and teenagers—2 milligrams (mg) every four to six hours as needed.
- Children 5 to 12 years of age—1 mg every four to six hours as needed.
- Children 4 to 5 years of age—0.5 mg every four to six hours as needed.
- Children and infants up to 4 years of age—Use is not recommended .
For long-acting oral dosage form (tablets):
- Adults—4 or 6 milligrams (mg) every eight to twelve hours as needed.
- Children 4 years of age and older—Use and dose must be determined by your doctor.
- Children and infants up to 4 years of age—Use is not recommended .

For oral dosage forms (capsules, tablets, or liquid):
- Adults and teenagers—25 to 50 milligrams (mg) every four to six hours as needed.
- Children 6 to 12 years of age—12.5 to 25 mg every four to six hours.
- Children 4 to 6 years of age—6.25 to 12.5 mg every four to six hours.
- Children and infants up to 4 years of age—Use is not recommended .
For injection dosage form:
- Adults—10 to 50 milligrams (mg) injected into a muscle or into a vein.
- Children 4 years of age and older—1.25 mg per kg (0.6 mg per pound) of body weight injected into a muscle four times a day.
- Children and infants up to 4 years of age—Use is not recommended .

For oral dosage form (tablets):
- Adults and teenagers—12.5 to 25 milligrams (mg) every four to six hours as needed.
- Children 6 to 12 years of age—6.25 to 12.5 mg every four to six hours as needed.
- Children 4 to 6 years of age—Use and dose must be determined by your doctor.
- Children and infants up to 4 years of age—Use is not recommended .

For oral dosage form (capsules):
- Adults and teenagers—60 milligrams (mg) two times a day as needed or 180 mg once a day.
- Children 6 to 11 years of age—30 mg twice a day as needed.
- Children 4 to 6 years of age—Use and dose must be determined by your doctor.
- Children and infants up to 4 years of age—Use is not recommended .

For oral dosage forms (tablets or liquid):
- Adults and children 6 years of age and older—10 milligrams (mg) once a day.
- Children 4 to 5 years of age—5 mg once a day.
- Children and infants up to 4 years of age—Use is not recommended .

For oral dosage form (tablets):
- Adults and teenagers—25 milligrams (mg) every four to six hours as needed.
- Children 6 to 12 years of age—12.5 mg every four to six hours as needed.
- Children 4 to 6 years of age—Use and dose must be determined by your doctor.
- Children and infants up to 4 years of age—Use is not recommended .

For nausea, vomiting, and vertigo (only dimenhydrinate and diphenhydramine are used for vertigo):

For regular (short-acting) oral dosage forms (tablets or liquid):
- Adults and teenagers—50 to 100 milligrams (mg) every four to six hours as needed.
- Children 6 to 12 years of age—25 to 50 mg every six to eight hours as needed.
- Children 4 to 6 years of age—12.5 to 25 mg every six to eight hours as needed.
- Children and infants up to 4 years of age—Use is not recommended .
For long-acting oral dosage forms (capsules):
- Adults—1 capsule (contains 25 milligrams [mg] for immediate action and 50 mg for long action) every twelve hours.
- Children 4 years of age and older—Use and dose must be determined by your doctor.
- Children and infants up to 4 years of age—Use is not recommended .
For injection dosage form:
- Adults—50 milligrams (mg) injected into a muscle or into a vein every four hours as needed.
- Children 2 years of age and older—1.25 mg per kg (0.6 mg per pound) of body weight injected into a muscle or into a vein every six hours as needed.
- Children and infants up to 4 years of age—Use is not recommended .
For suppository dosage form:
- Adults—50 to 100 milligrams (mg) inserted into the rectum every six to eight hours as needed.
- Children 12 years of age and older—50 mg inserted into the rectum every eight to twelve hours as needed.
- Children 8 to 12 years of age—25 to 50 mg inserted into the rectum every eight to twelve hours as needed.
- Children 6 to 8 years of age—12.5 to 25 mg inserted into the rectum every eight to twelve hours as needed.
- Children 4 to 6 years of age—Use and dose must be determined by your doctor.
- Children and infants up to 4 years of age—Use is not recommended .

For oral dosage forms (capsules, tablets, or liquid):
- Adults—25 to 50 milligrams (mg) every four to six hours as needed.
- Children 4 years of age and older—1 to 1.5 mg per kg (0.45 to 0.7 mg per pound) of body weight every four to six hours as needed.
- Children and infants up to 4 years of age—Use is not recommended .
For injection dosage form:
- Adults—10 milligrams (mg) injected into a muscle or into a vein. Dose may be increased to 25 to 50 mg every two to three hours.
- Children 4 years of age and older—1 to 1.5 mg per kg (0.45 to 0.68 mg per pound) of body weight injected into a muscle every six hours.
- Children and infants up to 4 years of age—Use is not recommended .

For oral dosage forms (capsules, tablets, or liquid):
- Adults—25 to 100 milligrams (mg) three or four times a day as needed.
- Children 6 years of age and older—12.5 to 25 mg every six hours as needed.
- Children 4 to 6 years of age—12.5 mg every six hours as needed.
- Children and infants up to 4 years of age—Use is not recommended .
For injection dosage form:
- Adults—25 to 100 milligrams (mg) injected into a muscle.
- Children 4 years of age and older—1 mg per kg (0.45 mg per pound) of body weight injected into a muscle.
- Children and infants up to 4 years of age—Use is not recommended .

For Parkinson's disease:

For oral dosage forms (capsules, tablets, or liquid):
- Adults—25 milligrams (mg) three times a day when starting treatment. Your doctor may increase the dose gradually later if needed.
For injection dosage form:
- Adults—10 to 50 milligrams (mg) injected into a muscle or into a vein.
- Children—1.25 mg per kg (0.6 mg per pound) of body weight four times a day injected into a muscle.

For use as a sedative (to help sleep):

For oral dosage forms (capsules, tablets, or liquid):
- Adults—50 milligrams (mg) twenty to thirty minutes before bedtime if needed.

For oral dosage form (tablets):
- Adults—25 milligrams (mg) thirty minutes before bedtime if needed.
- Children 4 years of age and older—Use and dose must be determined by your doctor.
- Children and infants up to 4 years of age—Use is not recommended .

For oral dosage forms (capsules, tablets, or liquid):
- Adults—50 to 100 milligrams (mg).
- Children 4 years of age and older—0.6 mg per kg (0.3 mg per pound) of body weight.
- Children and infants up to 4 years of age—Use is not recommended .
For injection dosage form:
- Adults—50 milligrams (mg) injected into a muscle.

For anxiety:

For oral dosage forms (capsules, tablets, or liquid):
- Adults—50 to 100 milligrams (mg).
- Children 4 years of age and older—0.6 mg per kg (0.3 mg per pound) of body weight.
- Children and infants up to 4 years of age—Use is not recommended .
For injection dosage form:
- Adults—50 to 100 milligrams (mg) injected into a muscle every four to six hours as needed.
- Children 4 years of age and older—1 mg per kilogram (0.45 mg per pound) of body weight injected into a muscle.
- Children and infants up to 4 years of age—Use is not recommended .

Missed dose—

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

Keep out of the reach of children.

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Do not keep outdated medicine or medicine no longer needed.

Precautions While Using This Medicine:

Before you have any skin tests for allergies, tell the doctor in charge that you are taking this medicine. The results of the test may be affected by this medicine.

When taking antihistamines on a regular basis, make sure your doctor knows if you are taking large amounts of aspirin at the same time (as for arthritis or rheumatism). Effects of too much aspirin, such as ringing in the ears, may be covered up by the antihistamine.

Antihistamines will add to the effects of alcohol and other CNS depressants (medicines that slow down the nervous system, possibly causing drowsiness). Some examples of CNS depressants are sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; barbiturates; medicine for seizures; muscle relaxants; or anesthetics, including some dental anesthetics. Check with your doctor before taking any of the above while you are using this medicine.

This medicine may cause some people to become drowsy or less alert than they are normally. Even if taken at bedtime, it may cause some people to feel drowsy or less alert on arising. Some antihistamines are more likely to cause drowsiness than others. Drowsiness is less likely with cetirizine, and rare with desloratadine and loratadine. Make sure you know how you react to the antihistamine you are taking before you drive, use machines, or do anything else that could be dangerous if you are not alert.

Antihistamines may cause dryness of the mouth, nose, and throat. Some antihistamines are more likely to cause dryness of the mouth than others . For temporary relief of mouth dryness, use sugarless candy or gum, melt bits of ice in your mouth, or use a saliva substitute. However, if your mouth continues to feel dry for more than 2 weeks, check with your medical doctor or dentist. Continuing dryness of the mouth may increase the chance of dental disease, including tooth decay, gum disease, and fungus infections.

For patients using dimenhydrinate, diphenhydramine, or hydroxyzine:

This medicine controls nausea and vomiting. For this reason, it may cover up the signs of overdose caused by other medicines or the symptoms of appendicitis. This will make it difficult for your doctor to diagnose these conditions. Make sure your doctor knows that you are taking this medicine if you have other symptoms of appendicitis such as stomach or lower abdominal pain, cramping, or soreness. Also, if you think you may have taken an overdose of any medicine, tell your doctor that you are taking this medicine.

For patients using diphenhydramine or doxylamine as a sleeping aid:

If you are already taking a sedative or tranquilizer, do not take this medicine without consulting your doctor first.

Side Effects of This Medicine:

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Less common or rare: Abdominal or stomach pain; burning; chills; clay-colored stools or dark urine; cough; diarrhea; difficulty swallowing; dizziness; fast or irregular heartbeat; fever; headache; hives; itching; prickly sensations; puffiness or swelling of the eyelids or around the eyes, face, lips or tongue; redness of skin; seizures; shortness of breath; skin rash; swelling; tightness in chest; tingling; unusual tiredness or weakness; wheezing

Check with your doctor as soon as possible if any of the following side effects occur:

Less common or rare: Sore throat; unusual bleeding or bruising; unusual tiredness or weakness

Symptoms of overdose: Clumsiness or unsteadiness; convulsions (seizures); drowsiness (severe); dryness of mouth, nose, or throat (severe); feeling faint; flushing or redness of face; hallucinations (seeing, hearing, or feeling things that are not there); shortness of breath or troubled breathing; trouble in sleeping

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common: Drowsiness; dry mouth, nose, or throat; gastrointestinal upset, stomach pain, or nausea; headache; increased appetite and weight gain; thickening of mucus

Less common or rare: Acid or sour stomach; belching; blurred vision or any change in vision; body aches or pain; clumsiness or unsteadiness; confusion (not with diphenhydramine); congestion; constipation; cough; diarrhea; difficult or painful urination; difficulty in moving; difficult or painful menstruation; dizziness (not with brompheniramine or hydroxyzine); drowsiness (with high doses of desloratadine and loratadine); dryness of mouth, nose, or throat; early menstruation; fast heartbeat; fever; heartburn; hoarseness; increased sensitivity of skin to sun; increased sweating; indigestion; loss of appetite; joint pain; muscle aching or cramping; muscle pains or stiffness; nausea; nightmares (not with azatadine, chlorpheniramine, cyproheptadine, desloratadine, hydroxyzine, or loratadine); ringing or buzzing in ears; runny nose; skin rash; swollen joints; stomach discomfort, upset or pain; tender swollen glands in neck; tremor; unusual excitement, nervousness, restlessness, or irritability; vomiting

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Last Updated: 11/16/2023

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