Guanfacine (By mouth)
Treats high blood pressure and 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.
- For patients with high blood pressure: Take the dose at bedtime unless your doctor tells you differently. This may help you avoid being drowsy during the day.
- For patients with ADHD: Take the extended-release tablet at the same time each day. 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.
- Missed dose: 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 the extended-release tablets for 2 or more days in a row.
- Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.
Drugs and Foods to Avoid
Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.
- Some foods and medicines can affect how guanfacine works. Tell your doctor if you are using any of the following:
- Carbamazepine, ketoconazole, rifampin
- Benzodiazepine medicine
- Medicine to treat seizures
- A phenothiazine medicine, such as chlorpromazine, perphenazine, promethazine, prochlorperazine, or thioridazine
- Do not drink alcohol while you are using this medicine.
- Tell your doctor if you use anything else that makes you sleepy. Some examples are allergy medicine, narcotic pain medicine, and alcohol.
Warnings While Using This Medicine
- Tell your doctor if you are pregnant or breastfeeding, or if you have kidney disease, liver disease, heart problems, blood vessel disease, low blood pressure, or had a recent heart attack or stroke.
- This medicine may cause low blood pressure. This can make you dizzy, drowsy, or lightheaded, especially if you are dehydrated. Do not drive or do anything else that could be dangerous until you know how this medicine affects you. Stand or sit up slowly if you feel lightheaded or dizzy.
- 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.
- Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments. Your doctor will also check your blood pressure and heart rate while you are using this medicine.
- Keep all medicine out of the reach of children. Never share your medicine with anyone.
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, trouble breathing
- Fast, slow, or uneven heartbeat
- Lightheadedness, dizziness, or fainting
If you notice these less serious side effects, talk with your doctor:
- Constipation, stomach pain
- Dry mouth
- Headache, trouble sleeping
- Tiredness or weakness
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 4/8/2016
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