This doesn t occur most of the time with MDMA. It has some vasoconstriction properties, but even so, Not common. sadly, the quality control of street drugs is very poor! another twenty different active substances were identified in these tablets, such as caffeine, 2C-B, piperazines, amphetamines, phencyclidine, and others in a scientific paper survey of MDMA in Brazil. Many of the chemicals involved in making it can cause local skin irritation and this is much more likely than a drug allergy. Over the counter benadryl (anti-histamine) would be helpful in allergy/itching. Antibacterial creme, looking out for pus, spreading redness, signs of getting sores infected (after soap and water cleaning out remaining chemical). Blood test for liver/kidney damage (this is very very rare; almost zero reported). MDMA is one of the worst drugs ever for causing permanent brain damage.