An unusual case of clarithromycin associated ergotism.

A 41-year-old woman presented to the Emergency Department complaining of a 4-day history of worsening lower leg pain, pallor, and a sensation of coolness aggravated by exertion. Evaluation revealed severe lower extremity vasospasm. She recently had been prescribed clarithromycin for "flu-like" symptoms, and for many years had been taking a caffeine-ergotamine preparation for migraine headaches. Clarithromycin is known to interfere with ergotamine metabolism. This drug interaction is often not recognized. Ergot alkaloids are commonly used for migraine headaches and have vasoconstrictive properties. In a patient with ergotamine toxicity, these vasoconstrictive properties can lead to frank ischemia. We reviewed the literature for reports of ergotamine-associated ischemia and for reports of ergotamine toxicity caused by drug-drug interaction.