Guanabenz Side Effects
Some side effects of guanabenz may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.
For the Consumer
Applies to guanabenz: oral tablet
Along with its needed effects, guanabenz 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 while taking guanabenz:Signs and symptoms of overdose
- Dizziness (severe)
- pinpoint pupils
- slow heartbeat
- unusual tiredness or weakness
Some side effects of guanabenz 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
- dryness of mouth
- Decreased sexual ability
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:
- 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
For Healthcare Professionals
Applies to guanabenz: compounding powder, oral tablet
In comparative studies the overall incidence of side effects associated with guanabenz 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.
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.
Gastrointestinal side effects include dry mouth in up to 37%, constipation in 2%, and nausea in 1% of patients.
Postural hypotension may not have been observed, at least during initial therapy with guanabenz, due to peripheral vascular resistance and cardiac output remaining unchanged.
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.
Nasal congestion has been reported in less than 3% of patients.
Dermatologic rashes have been reported in less than 3% of patients.
Ocular side effects are limited to rare cases of blurry vision.
There are no serious endocrinologic side effects associated with guanabenz. 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.
There are no known clinically significant renal side effects from guanabenz. 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.
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.
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