Wytensin

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.

Applies to guanabenz: compounding powder, oral tablet

Other

In comparative studies the overall incidence of side effects associated with guanabenz (the active ingredient contained in Wytensin) was as high or higher than that seen with methyldopa or clonidine, but particularly troublesome effects, such as sodium retention, mental depression or sexual dysfunction, which have been associated with these drugs, have not been associated with guanabenz.[Ref]

Nervous system

The most common side effects involve the nervous system. Drowsiness is a complaint in up to 35% of patients, and, with dry mouth, is the main reason some patients discontinue therapy. Weakness or dizziness each occur in 6% and headache in 2% in patients.[Ref]

Gastrointestinal

Gastrointestinal side effects include dry mouth in up to 37%, constipation in 2%, and nausea in 1% of patients.[Ref]

Cardiovascular

Postural hypotension may not have been observed, at least during initial therapy with guanabenz (the active ingredient contained in Wytensin) due to peripheral vascular resistance and cardiac output remaining unchanged.[Ref]

Although usually asymptomatic, guanabenz can decrease heart rate. Other cardiovascular side effects are rare. Unlike some other alpha-2-adrenoreceptor agonists, guanabenz is only rarely associated with orthostatic hypotension. Rebound hypertension can be a significant problem that may be accompanied by nervousness, palpitations, diaphoresis, anxiety, insomnia, malaise, and abdominal cramps. It has been observed anywhere from 16 to 72 hours after discontinuation of therapy.[Ref]

Respiratory

Nasal congestion has been reported in less than 3% of patients.[Ref]

Dermatologic

Dermatologic rashes have been reported in less than 3% of patients.[Ref]

Ocular

Ocular side effects are limited to rare cases of blurry vision.[Ref]

Endocrine

There are no serious endocrinologic side effects associated with guanabenz (the active ingredient contained in Wytensin) The drug does not appear to adversely affect the lipid profile. Some data indicate significant decreases in total and LDL cholesterol levels during guanabenz therapy.[Ref]

Renal

There are no known clinically significant renal side effects from guanabenz (the active ingredient contained in Wytensin) Acutely (within the first day of therapy), guanabenz may cause a mild water diuresis. Unlike some alpha-2-adrenoreceptor agonists, guanabenz is not associated with sodium and water retention.[Ref]

Some data have shown significant increases in glomerular filtration rate, natriuresis, and free water clearance associated with the use of guanabenz during the first few hours of therapy. Use of guanabenz for one week or more, however, has not been associated with significant changes in renal function parameters.[Ref]

Some side effects of Wytensin may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.