-certain medicines for blood pressure, heart disease, irregular heart beat
-certain medicines for depression, anxiety, or psychotic disturbances
-certain medicines for seizures like carbamazepine, phenobarbital, phenytoin
-certain medicines for sleep
-ketoconazole
-narcotic medicines for pain
-rifampin

They need to know if you have any of these conditions:

-heart disease or recent heart attack
-kidney disease
-liver disease
-history of stroke
-an unusual or allergic reaction to guanfacine, other medicines, foods, dyes, or preservatives
-pregnant or trying to get pregnant
-breast-feeding

Visit your doctor or health care professional for regular checks on your progress. Check your heart rate and blood pressure regularly while you are taking this medicine. Ask your doctor or health care professional what your heart rate should be and when you should contact him or her.
You may get drowsy or dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how this medicine affects you. To avoid dizzy or fainting spells, do not stand or sit up quickly, especially if you are an older person. Alcohol can make you more drowsy and dizzy. Avoid alcoholic drinks.
Avoid becoming dehydrated or overheated while taking this medicine.
Your mouth may get dry. Chewing sugarless gum or sucking hard candy, and drinking plenty of water may help. Contact your doctor if the problem does not go away or is severe.
Do not treat yourself for coughs, colds or allergies without asking your doctor or health care professional for advice. Some ingredients can increase your blood pressure.

Keep out of the reach of children and pets.
Store at room temperature between 20 and 25 degrees C (68 and 77 degrees F). Throw away any unused drug after the expiration date.