You should not use this medication if you are allergic to guanfacine.
Before taking guanfacine, tell your doctor if you have heart disease, coronary artery disease or a history of stroke, kidney disease, liver disease, or if you have recently had a heart attack.
Do not stop taking this medication without first talking to your doctor. If you stop taking guanfacine suddenly, your condition may become worse and you could have unpleasant symptoms.
To be sure this medication is helping your condition, your blood pressure will need to be checked on a regular basis. Do not miss any scheduled appointments.
Avoid drinking alcohol. It can increase some of the side effects of guanfacine.
Guanfacine can cause drowsiness and should be taken at bedtime unless your doctor has told you otherwise.
Tell your doctor if you regularly use other medicines that make you sleepy (such as cold or allergy medicine, narcotic pain medicine, sleeping pills, muscle relaxers, and medicine for seizures, depression, or anxiety). They can add to sleepiness caused by guanfacine.