Before taking this medication, tell your doctor if you
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have any type of heart disease,
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have had a heart attack or a stroke,
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have kidney disease, or
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have liver disease.
You may need a lower dose or special monitoring during treatment with guanfacine if you have any of the conditions listed above.
Guanfacine is in the FDA pregnancy category B. This means that it is unlikely to harm an unborn baby. Do not take guanfacine without first talking to your doctor if you are pregnant.
It is not known whether guanfacine passes into breast milk and how it might affect a nursing infant. Do not take guanfacine without first talking to your doctor if you are breast-feeding a baby.
If you are over 60 years of age, you may be more likely to experience side effects from guanfacine therapy. You may require a lower dose.
The FDA has not approved guanfacine for use by children younger than 12 years of age.
Take guanfacine exactly as directed by your doctor. If you do not understand these directions, ask your pharmacist, nurse, or doctor to explain them to you.
Take each dose with a full glass of water.
Take guanfacine at bedtime unless otherwise directed by your doctor. This medication may make you drowsy and may cause some dizziness. Taking it at bedtime may help to prevent falls and injuries.
Do not stop taking this medication suddenly even if you feel better. Taking this medication regularly is important in the treatment of your condition.
Store this medication at room temperature away from moisture and heat.
Take the missed dose as soon as you remember. However, if it is almost time for your next
dose, skip the dose you missed and take only your next regularly scheduled dose.
If you experience any of the following serious side effects, stop taking guanfacine and seek emergency medical attention:
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an allergic reaction (difficulty breathing; closing of your throat; swelling of your lips, tongue, or face; or hives);
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a very slow heart rate (fewer than 60 beats per minute); or
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unusually high or low blood pressure (fainting, a severe headache, flushing of your face).
Other, less serious side effects may be more likely to occur. Continue to take guanfacine and talk to your doctor if you experience any of the following:
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unusual fatigue, dizziness, or tiredness;
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headache;
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constipation, nausea, vomiting, or diarrhea;
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insomnia; or
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dry mouth (sucking on ice chips or sugarless hard candy may relieve this side effect).
Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.
Do not stop taking guanfacine suddenly. Stopping suddenly could cause severely high blood pressure, nervousness, and anxiety.
Use caution when driving, operating machinery, or performing other hazardous activities. Guanfacine may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities.
Use caution when rising from a sitting or lying position and take guanfacine at bedtime if possible. Guanfacine will make you drowsy and may cause some dizziness.
Do not use alcohol, antihistamines, prescription pain relievers, sleeping pills, and other drugs that may cause drowsiness or dizziness except under the supervision of your doctor.
Use caution when driving, operating machinery, or performing other hazardous activities. Guanfacine may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities.
Avoid alcohol while taking guanfacine. Alcohol may increase the drowsiness you experience from guanfacine therapy and may also increase dizziness. Use caution even with small amounts of alcohol.
Do not take other drugs such as sleeping pills, prescription pain relievers, antihistamines, or antidepressants without first talking to your doctor. These medicines may increase the drowsiness caused by guanfacine. Talk to your doctor or pharmacist about any other prescription or over-the-counter medications you are taking.
Guanfacine may increase the effects of other drugs that cause drowsiness, including antidepressants, alcohol, antihistamines, sedatives (used to treat insomnia), pain relievers, anxiety medicines, and muscle relaxants. Tell your doctor about all medicines that you are taking, and do not take any medicine unless your doctor approves.
Drugs other than those listed here may also interact with guanfacine or affect your condition. Talk to your doctor and pharmacist before taking any prescription or over-the-counter medicines.
Seek emergency medical attention.
Symptoms of a guanfacine overdose include drowsiness, a sluggish feeling, weakness, lightheadedness, a slow heart rate, nausea, vomiting, and possibly seizures.