DRUG INTERACTIONS: Infrequently, a very serious, life-threatening decrease in the amount of blood supply to the hands and feet (peripheral ischemia) and rarely to the brain can occur when this medication is taken with drugs that affect liver metabolism (e.g., potent CYP 3A4 enzyme inhibitors). Do not take this medication with macrolide antibiotics (e.g., erythromycin, clarithromycin, troleandomycin), protease inhibitors (e.g., ritonavir, nelfinavir, indinavir, amprenavir, saquinavir), azole antifungals (e.g., ketoconazole, itraconazole). Tell your doctor of all over-the-counter or prescription medications you may use including: propranolol, high blood pressure medication, blood thinners, sedatives, narcotic pain relievers, sleeping pills, nitrates (e.g., isosorbide, nitroglycerin), nefazodone, fluconazole, fluoxetine, fluvoxamine, zileuton, clotrimazole, other mild CYP 3A4 enzyme inhibitors. Avoid eating grapefruit or drinking grapefruit juice while using this medication unless your doctor instructs you otherwise. This drug may interfere with the effectiveness of birth control pills. Discuss using other methods of birth control with your doctor. Avoid drinking caffeine-containing beverages (coffee, tea, colas) and eating large amounts of chocolate. Because this medication contains caffeine, the risk of side effects may be increased. Do not start or stop any medicine without doctor or pharmacist approval.

OVERDOSE: If overdose is suspected, contact your local poison control center or emergency room immediately. US residents can call the US national poison hotline at 1-800-222-1222. Canadian residents should call their local poison control center directly. Symptoms of overdose may include blurred vision, dilated pupils, hot and dry skin, dizziness, dryness of mouth, and slow or shallow breathing.

NOTES: This medication is used to treat a headache once it occurs. It is not effective in preventing a migraine headache from occurring. This medication is not to be taken to treat an ordinary headache.

MISSED DOSE: This medication is not taken routinely. As with most medications, if you miss a dose, do not "double-up" the dose to catch up.

STORAGE: Store at room temperature between 59 and 86 degrees F (15 to 30 degrees C) away from heat and light. Do not store in the bathroom. Keep out of reach of children.

Report Problems to the Food and Drug Administration You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088. Need help identifying pills and medications? Use the pill identifier tool on RxList.