This medication is used alone or with other medications to treat high blood pressure (hypertension). Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. Guanabenz belongs to a class of drugs known as centrally acting antihypertensives. It works by decreasing the levels of certain brain chemicals (neurotransmitters), thereby relaxing blood vessels and decreasing blood pressure.
OTHER USES: This section contains uses of this drug that are not listed in the approved professional labeling for the drug but that may be prescribed by your health care professional. Use this drug for a condition that is listed in this section only if it has been so prescribed by your health care professional.
This drug may also be used with other medications to decrease symptoms of withdrawal from narcotic pain medications.

How to use Wytensin Oral
Take this medication by mouth, usually twice daily or exactly as prescribed by your doctor. You may take this medication with or without food, but it is important to choose one and take this drug that way each time. If you have intolerable side effects during the day, your doctor may instruct you to take your total daily dose at bedtime.
Dosage is based on your medical condition, tolerance of side effects, and response to treatment. The dose will be gradually increased every 1 to 2 weeks until the best dose for you is reached.
Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time(s) each day. It is important to continue taking this medication even if you feel well. Most people with high blood pressure do not feel sick. It may take up to several weeks before the full benefit of this drug takes effect.
Do not stop taking this medication without first consulting your doctor. Some conditions may become worse when the drug is abruptly stopped. Your dose may need to be gradually decreased.
Tell your doctor if your condition worsens (e.g., your routine blood pressure readings increase) or you experience severe side effects.

Drowsiness, dry mouth, dizziness, and weakness may occur. Less common side effects may include headache, stuffy nose, dry eyes, blurred vision, nausea, vomiting, stomach pain/discomfort, diarrhea, constipation, and unusual taste in the mouth. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.
To relieve dry mouth, suck on (sugarless) hard candy or ice chips, chew (sugarless) gum, drink water, or use a saliva substitute. To help prevent constipation, eat adequate fiber, drink plenty of fluids, and exercise. If constipation occurs, ask your pharmacist for help selecting a laxative.
Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
Tell your doctor immediately if any of these unlikely but serious side effects occur: unusual sweating, unusually slow heartbeat, sudden pounding heartbeat, decreased sexual ability/interest, muscle pain, increase in urine, enlargement of breasts, depression.
A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US -
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Before taking guanabenz, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.
Before using this medication, tell your doctor or pharmacist your medical history, especially of: liver problems, kidney problems, severely blocked heart blood vessels (coronary artery disease), severe and returning chest pain (angina), heart attack in the last year, blockage of blood vessels in the brain (cerebrovascular disease).
This drug may cause dizziness or drowsiness. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Use of alcohol or certain other medications that cause drowsiness could increase these effects (see Drug Interactions section). Limit alcoholic beverages.
Caution is advised when using this drug in the elderly because they may be more sensitive to the effects of the drug, especially drowsiness and dizziness.
Before having surgery, tell your doctor or dentist that you are taking this medication.
During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.
It is not known whether this drug passes into breast milk. Consult your doctor before breast-feeding.

Your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor or pharmacist first.
Before using this medication, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially of: MAO inhibitors (isocarboxazid, linezolid, methylene blue, moclobemide, phenelzine, procarbazine, rasagiline, selegiline, tranylcypromine), other blood pressure medications (e.g., beta blockers such as propranolol, diuretics such as hydrochlorothiazide, calcium channel blockers such as nifedipine or amlodipine, ACE inhibitors such as lisinopril).
If you are currently using any of these medications listed above, tell your doctor or pharmacist before starting guanabenz.
Before using this medication, tell your doctor or pharmacist if you use any other prescription and nonprescription products that cause drowsiness such as certain antihistamines (e.g., diphenhydramine), anti-seizure drugs (e.g., carbamazepine), medicine for sleep or anxiety (e.g., alprazolam, diazepam, zolpidem), muscle relaxants (e.g., methocarbamol), narcotic pain relievers (e.g., codeine), psychiatric medicines (e.g., chlorpromazine, risperidone, trazodone).
Check the labels on all your medicines (such as cough-and-cold products, diet aids, or NSAIDs such as ibuprofen, naproxen) because they may contain ingredients that could increase your blood pressure. Ask your pharmacist for more details.
This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist.

If overdose is suspected, contact your local poison control center or emergency room immediately. US residents can call the US National Poison Hotline at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: severe drowsiness/dizziness, severe weakness, irritability, unusually small pupils, unusually slow heartbeat, fainting.

NOTES:
Do not share this medication with others.
Lifestyle changes such as stress reduction programs, exercise, and dietary changes may increase the effectiveness of this medicine. Talk to your doctor or pharmacist about lifestyle changes that might benefit you.
Keep all medical appointments so that your doctor can monitor your progress or check for side effects. Consult your doctor for more details.
Have your blood pressure checked regularly while taking this medication. Learn how to monitor your own blood pressure, and share the readings with your doctor.

MISSED DOSE:
If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.

STORAGE:
Store at room temperature between 59-86 degrees F (15-30 degrees C) away from light and moisture. Do not store in the bathroom. Keep all medicines away from children and pets.
Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.
Information last revised March 2012. Copyright(c) 2012 First Databank, Inc.