Purchase Guanfacine from Amber lifesciences, is available in tablet form with strengths typically ranging from 1 mg to 4 mg. It is used to treat attention deficit hyperactivity disorder and hypertension (high blood pressure) by affecting certain receptors in the brain and relaxing blood vessels. The dosage and frequency of administration depend on the condition being treated, the patient's response to the medication and treatment suggested by healthcare physician. Common side effects may include drowsiness, dizziness, dry mouth, and constipation.