HISTORY AND ADMISSION FINDINGS: A 57-year-old woman, a heavy smoker and migraine sufferer, was admitted with severe resting pain in the right forefoot and painful localized tendril-shaped reddening on the right thigh. She had regularly been taking 1-2 mg ergotamine tartrate, several analgesics, some containing caffeine, and selective serotonin-uptake inhibitors. Clinical examination found all limbs to be cool. On the right leg the pulse was not palpable below the inguinal line, and the reddening corresponded to localized livedo. INVESTIGATIONS: The peripheral Doppler pressure indicated critical perfusion reduction in the right leg with a tibiobrachial pressure ratio of 0.14. Colour-coded duplex sonography showed generalized vasoconstriction with filiform hourglass stenosis of the right proximal superficial femoral artery without atherosclerotic changes. The history of drug intake and the characteristic sonographic findings indicated ergotism and an arteriography was deemed unnecessary. TREATMENT AND COURSE: All ergotamine and caffeine containing drugs were discontinued and the patient urged to stop smoking. Amlidopine, 2.5 mg orally, and prostaglandin E1, 60 microgram i.v., were administered daily. The resting pain was much reduced after the first infusion and the painful livedo disappeared. The documented high-grade stenosis of the right superficial femoral artery was reduced to 25-50% by the third day of infusion. At the end of 10 daily infusions both the Doppler pressure and the duplex sonography had become normal. Pizotifen was given for the migraine and the serotonin re-uptake inhibitor sertralin was discontinued. CONCLUSION: An interaction of the serotonin re-uptake inhibitor with ergotamine was presumably responsible for the development of ergotism under >>therapeutic<< ergotamine dosage. Vasospastic stenoses and occlusions can be demonstrated by duplex sonography and may in future not require additional angiographic confirmation. Intravenous rather than intraarterial infusion of prostaglandin is to be preferred if vessels at many sites are affected. Livedo is a transitory sign of ergotism.