Generic Name: guanfacine (GWAHN-fa-seen)
Brand Name: Tenex
Guanfacine is used for:
Treating high blood pressure. It may be used alone or with other medicines. It may also be used for other conditions as determined by your doctor.
Guanfacine is an alpha agonist. It works by relaxing (dilating) blood vessels and decreasing heart rate, which lowers blood pressure.
Do NOT use guanfacine if:
- you are allergic to any ingredient in guanfacine
Contact your doctor or health care provider right away if any of these apply to you.
Before using guanfacine:
Some medical conditions may interact with guanfacine. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:
- if you are pregnant, planning to become pregnant, or are breast-feeding
- if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
- if you have allergies to medicines, foods, or other substances
- if you have liver or kidney problems, or the blood disorder porphyria
- if you have blood vessel disease affecting the brain or severe heart disease, or have had a stroke or a recent heart attack
- if you are scheduled for surgery
Some MEDICINES MAY INTERACT with guanfacine. Tell your health care provider if you are taking any other medicines, especially any of the following:
- Barbiturates (eg, phenobarbital) or hydantoins (eg, phenytoin) because they may increase the risk of guanfacine's side effects
- Beta-blockers (eg, propranolol), calcium channel blockers (eg, verapamil), or digitalis because a severe decrease in heart rate may occur
- Tricyclic antidepressants (eg, amitriptyline) because they may decrease guanfacine's effectiveness and increase the risk of certain side effects
This may not be a complete list of all interactions that may occur. Ask your health care provider if guanfacine may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.
How to use guanfacine:
Use guanfacine as directed by your doctor. Check the label on the medicine for exact dosing instructions.
- Take guanfacine by mouth with or without food.
- Guanfacine works best if it is taken at the same time each day.
- Continue to use guanfacine even if you feel well. Do not miss any doses.
- If you miss a dose of guanfacine, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.
Ask your health care provider any questions you may have about how to use guanfacine.
Important safety information:
- Guanfacine may cause drowsiness, dizziness, or lightheadedness. These effects may be worse if you take it with alcohol or certain medicines. Use guanfacine with caution. Do not drive or perform other possibly unsafe tasks until you know how you react to it.
- Do not drink alcohol or use medicines that may cause drowsiness (eg, sleep aids, muscle relaxers) while you are using guanfacine; it may add to their effects. Ask your pharmacist if you have questions about which medicines may cause drowsiness.
- Guanfacine may cause dizziness, lightheadedness, or fainting; alcohol, hot weather, exercise, or fever may increase these effects. To prevent them, sit up or stand slowly, especially in the morning. Sit or lie down at the first sign of any of these effects.
- Do not suddenly stop taking guanfacine without talking to your doctor. Excessive elevations in blood pressure and symptoms such as nervousness, headache, and confusion may occur if guanfacine is suddenly stopped.
- Patients who take medicine for high blood pressure often feel tired or run down for a few weeks after starting treatment. Be sure to take your medicine even if you may not feel "normal". Tell your doctor if you develop any new symptoms.
- If you experience dry mouth, use sugarless candy or gum, or melt bits of ice in your mouth to help keep your mouth moist.
- Tell your doctor or dentist that you take guanfacine before you receive any medical or dental care, emergency care, or surgery.
- Lab tests, including blood pressure, may be performed while you use guanfacine. These tests may be used to monitor your condition or check for side effects. Be sure to keep all doctor and lab appointments.
- Use guanfacine with caution in the ELDERLY; they may be more sensitive to its effects, especially dizziness.
- Guanfacine should not be used in CHILDREN younger than 12 years old; safety and effectiveness in these children have not been confirmed.
- PREGNANCY and BREAST-FEEDING: If you become pregnant, contact your doctor. You will need to discuss the benefits and risks of using guanfacine while you are pregnant. It is not known if guanfacine is found in breast milk. If you are or will be breast-feeding while you use guanfacine, check with your doctor. Discuss any possible risks to your baby.
If you suddenly stop taking guanfacine, you may experience WITHDRAWAL symptoms, including nervousness, agitation, headache, tremor, and rapid increase in blood pressure.
Possible side effects of guanfacine:
All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome:
Seek medical attention right away if any of these SEVERE side effects occur:
Constipation; dizziness; drowsiness; dry mouth; tiredness.
Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); changes in heartbeat; inability to have sex; pounding in the chest.
This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.
If OVERDOSE is suspected:
Contact 1-800-222-1222 (the American Association of Poison Control Centers), your local poison control center, or emergency room immediately. Accidental overdose of guanfacine is an increasing cause of poisoning in children 3 years of age and younger. Symptoms may include difficult or slow breathing; drowsiness leading to unresponsiveness or coma; irritability; lightheadedness, especially upon standing; pinpoint pupils; slow heartbeat; vomiting; weakness.Proper storage of guanfacine:
Store guanfacine between 68 and 77 degrees F (20 and 25 degrees C). Store away from heat, moisture, and light. Do not store in the bathroom. Keep guanfacine out of the reach of children and away from pets.
- If you have any questions about guanfacine, please talk with your doctor, pharmacist, or other health care provider.
- Guanfacine is to be used only by the patient for whom it is prescribed. Do not share it with other people.
- If your symptoms do not improve or if they become worse, check with your doctor.
- Check with your pharmacist about how to dispose of unused medicine.
This information should not be used to decide whether or not to take guanfacine or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about guanfacine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to guanfacine. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using guanfacine.
Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using this medicine.