Guanfacine (By mouth)
Treats high blood pressure. Also treats attention deficit hyperactivity disorder (ADHD).
When This Medicine Should Not Be Used
How to Use This Medicine
Tablet, Long Acting Tablet
- Take your medicine as directed. Your dose may need to be changed several times to find what works best for you.
- If you are taking guanfacine once a day, take the dose at bedtime unless your doctor tells you differently. This may help you avoid being drowsy during the day.
- Take the extended-release tablet once a day, either in the morning or evening. It should not be taken with high-fat meals.
- Swallow the extended-release tablet whole. Do not crush, break, or chew it.
- Read and follow the patient instructions that come with this medicine. Talk to your doctor or pharmacist if you have any questions.
If a dose is missed:
- Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
- Check with your doctor if you miss your dose of guanfacine extended-release tablets for 2 or more days in a row.
How to Store and Dispose of This Medicine
- Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.
- Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.
- Keep all medicine out of the reach of children. Never share your medicine with anyone.
Drugs and Foods to Avoid
Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.
- Make sure your doctor knows if you also use St John's wort, conivaptan (Vaprisol®), medicine to lower blood pressure (such as amlodipine, atenolol, clonidine, hydrochlorothiazide, lisinopril, metoprolol, Benicar®, Cozaar®, Diovan®), medicine to treat an infection (such as clarithromycin, itraconazole, ketoconazole, posaconazole, rifampin, telithromycin, voriconazole, Nizoral®, Rifadin®, Rimactane®), medicine to treat hepatitis C (such as boceprevir, telaprevir, Incivek®, Victrelis®), medicine to treat HIV/AIDS (such as indinavir, lopinavir/ritonavir, nelfinavir, ritonavir, saquinavir, Crixivan®, Kaletra®), medicine to treat depression (such as nefazodone, Serzone®), a benzodiazepine medicine (such as alprazolam, clonazepam, diazepam, lorazepam, Xanax®), medicine for seizures (such as carbamazepine, phenobarbital, phenytoin, valproic acid, Depakene®, Dilantin®, Tegretol®), or a phenothiazine medicine (such as promethazine, Phenergan®, Thorazine®).
- Do not eat grapefruit or drink grapefruit juice while you are using this medicine.
- Tell your doctor if you drink alcohol or if you are using any medicine that makes you sleepy, such as allergy medicine or narcotic pain medicine.
Warnings While Using This Medicine
- Make sure your doctor knows if you are pregnant or breastfeeding or if you have kidney disease, liver disease, or depression. Tell your doctor if you have a history of heart or blood vessel disease, heart block, fainting, low blood pressure, slow heart rate, or have had a recent heart attack or stroke. Tell your doctor if you drink alcohol.
- Do not stop using this medicine suddenly. Your doctor will need to slowly decrease your dose before you stop it completely.
- Tell any doctor or dentist who treats you that you are using this medicine. You may need to stop using this medicine several days before you have surgery or medical tests.
- This medicine may make you dizzy, drowsy, faint, or lightheaded. Do not drive, use machines, or do anything else that could be dangerous until you know how this medicine affects you. Stand or sit up slowly if you are dizzy.
- If you take this medicine for blood pressure, do not stop using it without asking your doctor, even if you feel well. This medicine will not cure your high blood pressure, but it will help keep it in normal range. You may have to take blood pressure medicine for the rest of your life.
- If you take this medicine for ADHD, it is part of a treatment program that may also include counseling or special education. Carefully follow your doctor's instructions about all treatment measures.
- Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.
Possible Side Effects While Using This Medicine
Call your doctor right away if you notice any of these side effects:
- Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
- Chest pain
- Lightheadedness, dizziness, or fainting
- Slow or uneven heartbeat
- Trouble breathing
- Unusual tiredness or weakness
If you notice these less serious side effects, talk with your doctor:
- Constipation, nausea, stomach pain
- Dry mouth
- Trouble sleeping
- Unusual drowsiness or sleepiness
If you notice other side effects that you think are caused by this medicine, tell your doctor
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088
- Last reviewed on 8/4/2014
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