What should I know about guanfacine before taking it?

Do not take guanfacine if you are allergic to it or any of its ingredients. Tell your doctor before taking guanfacine if you have recently had a heart attack, if you have ever had a stroke or fainted. Tell your doctor before taking guanfacine if you have a history of low blood pressure, bipolar disorder, a blood disorder, slow heart rate or kidney, liver, or heart disease. Guanfacine is considered safe for use during pregnancy and breastfeeding. However, you should talk to your doctor before taking guanfacine if you are pregnant, plan to become pregnant or are breastfeeding.

If you must have surgery, tell the surgeon or dentist that you are taking guanfacine. It may cause dizziness and fainting. Alcohol, heat and dehydration can worsen these side effects. Talk to your doctor about using alcohol safely while taking guanfacine. Drink plenty of fluids while taking guanfacine to avoid dehydration. Stand up slowly from a sitting or reclining position while taking guanfacine. Do not drive or operate machinery or tools until you know how guanfacine will affect you. Abruptly discontinuing guanfacine may lead to withdrawal symptoms, such as nervousness, tremors or rapid blood pressure elevation.

Guanfacine can have a number of drug interactions. Talk to your doctor before taking guanfacine if you are taking any of the following:

  • antihistamines
  • antidepressants
  • barbiturates
  • clarithromycin
  • itraconazole
  • indinavir
  • carbamazepine
  • ketoconazole
  • drugs for high blood pressure, anxiety, seizures, nausea or mental illness
  • pioglitazone
  • phenytoin
  • nelfinavir
  • nefazodone
  • rifabutin
  • rifampin
  • ritonavir
  • sleeping pills, sedatives or tranquilizers
  • beta-blockers
  • calcium channel blockers
  • digitalis

Guanfacine can interact with some vitamins and supplements, including St. John's Wort. Tell your doctor about any other prescription or over-the-counter drugs, vitamins or supplements you are taking before taking guanfacine.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.