Guanfacine hydrochloride

• Side effects may include:
  Constipation, dizziness, dry mouth, fatigue, headache, impotence, sleepiness, weakness

Some of these side effects may lessen or disappear as your body gets used to guanfacine.

Why should Guanfacine hydrochloride not be prescribed?

Do not take guanfacine if you are sensitive to it or have ever had an allergic reaction to it.

Guanfacine is not recommended for controlling the severe high blood pressure that accompanies toxemia of pregnancy (a disorder of pregnant women characterized by a rise in blood pressure, swelling, and leakage of protein into urine).

Special warnings about Guanfacine hydrochloride

While taking guanfacine, you should be monitored very closely by your doctor if you have any of the following medical conditions:

Chronic kidney or liver failure
Heart disease
History of stroke
Recent heart attack

Since guanfacine causes drowsiness and may also make you dizzy, do not drive, climb, or perform hazardous tasks until you find out exactly how Guanfacine hydrochloride affects you.

While taking guanfacine, use alcoholic beverages with care; you may feel intoxicated after drinking only a small amount of alcohol.

If you have kidney damage and also take the antiseizure drug phenytoin (Dilantin), your body may process and eliminate guanfacine rather quickly; in that case, you may need fairly frequent doses of guanfacine to lower your blood pressure adequately.

If you have been taking guanfacine for a while, do not stop taking it without consulting your doctor. Discontinuing abruptly may result in nervousness, rapid pulse, anxiety, heartbeat irregularities, and so-called rebound high blood pressure (higher than before you started taking guanfacine). If you do have rebound high blood pressure, it will probably develop 2 to 4 days after your last dose of guanfacine. Rebound high blood pressure, if it occurs, will usually diminish and then disappear over a period of 2 to 4 days.

Possible food and drug interactions when taking Guanfacine hydrochloride

If guanfacine is taken with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining guanfacine with the following:

Barbiturates such as Amytal, Seconal, Tuinal, and others
Benzodiazepines such as Tranxene, Valium, Xanax, and others
Phenothiazines such as Mellaril, Stelazine, Thorazine, and others
Phenytoin (Dilantin)