Guanabenz (Oral route)
Alpha-2 Adrenergic Agonist
Uses of This Medicine:
Guanabenz belongs to the general class of medicines called antihypertensives. It is used to treat high blood pressure (hypertension).
High blood pressure adds to the work load of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain, heart, and kidneys, resulting in a stroke, heart failure, or kidney failure. High blood pressure may also increase the risk of heart attacks. These problems may be less likely to occur if blood pressure is controlled.
Guanabenz works by controlling nerve impulses along certain nerve pathways. As a result, it relaxes blood vessels so that blood passes through them more easily. This helps to lower blood pressure.
Guanabenz is available only with your doctor's prescription.
Before Using This Medicine:
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to this medicine 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.
Studies on this medicine have been done only in adult patients, and there is no specific information comparing use of guanabenz in children with use in other age groups.
Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of guanabenz in the elderly with use in other age groups. However, dizziness, faintness, or drowsiness may be more likely to occur in the elderly, who are usually more sensitive to the effects of guanabenz.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
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 this medicine, 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 this medicine 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.
- Iobenguane I 131
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
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.
Other medical problems—
The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:
- Heart or blood vessel disease—Lowering blood pressure may make some conditions worse
- Kidney disease or
- Liver disease—Effects of guanabenz may be increased because of slower removal of guanabenz from the body
Proper Use of This Medicine:
In addition to the use of the medicine your doctor has prescribed, treatment for your high blood pressure may include weight control and care in the types of foods you eat, especially foods high in sodium. Your doctor will tell you which of these are most important for you. You should check with your doctor before changing your diet.
Many patients who have high blood pressure will not notice any signs of the problem. In fact, many may feel normal. It is very important that you take your medicine exactly as directed and that you keep your appointments with your doctor even if you feel well.
Remember that this medicine will not cure your high blood pressure but it does help control it. Therefore, you must continue to take it as directed if you expect to lower your blood pressure and keep it down. You may have to take high blood pressure medicine for the rest of your life . If high blood pressure is not treated, it can cause serious problems such as heart failure, blood vessel disease, stroke, or kidney disease.
To help you remember to take your medicine, try to get into the habit of taking it at the same time each day.
The dose of this medicine 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 this medicine. 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 oral dosage form (tablets):
- For high blood pressure:
- Adults—At first, 4 milligrams (mg) two times a day. Then, your doctor may gradually increase your dose.
- Children—Use and dose must be determined by your doctor.
- For high blood pressure:
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.
If you miss two or more doses in a row, check with your doctor. If your body suddenly goes without this medicine, some unpleasant effects may occur. If you have any questions about this, check with your doctor.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Precautions While Using This Medicine:
It is important that your doctor check your progress at regular visits to make sure that this medicine is working properly.
Check with your doctor before you stop taking guanabenz. Your doctor may want you to reduce gradually the amount you are taking before stopping completely.
Before having any kind of surgery (including dental surgery) or emergency treatment, tell the medical doctor or dentist in charge that you are using this medicine.
Do not take other medicines unless they have been discussed with your doctor. This especially includes over-the-counter (nonprescription) medicines for appetite control, asthma, colds, cough, hay fever, or sinus problems, since they may tend to increase your blood pressure.
Guanabenz 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 antihistamines or medicine for hay fever, other allergies, or colds; 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.
Guanabenz may cause some people to become dizzy, drowsy, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert.
Guanabenz may cause dryness of the mouth, nose, and throat. 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.
Side Effects of This Medicine:
- Signs and symptoms of overdose
- Dizziness (severe)
- pinpoint pupils
- slow heartbeat
- unusual tiredness or weakness
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 as soon as possible if any of the following side effects occur:
- More common
- dryness of mouth
- Less common or rare
- Decreased sexual ability
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:
- Anxiety or tenseness
- chest pain
- fast or irregular heartbeat
- increased salivation
- increase in sweating
- nausea or vomiting
- nervousness or restlessness
- shaking or trembling of hands or fingers
- stomach cramps
- trouble in sleeping
After you stop using this medicine, it may still produce some side effects that need attention. During this period of time, check with your doctor immediately if you notice the following side effects:
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: 8/5/2022