Will an ecstasy overdose have long lasting side effects?

Long term effects: This is still being researched. Reduction in serotonin is present after awhile and behavioral changes with mood can be found. Some increaised apoptosis has been noted.

It may.: Ecstasy overdose can cause palpitations, chest pain, heart attack, heart failure, pulmonary hypertension, stroke, be toxic to the heart, angina pectoris, destruction of blood vesselscoma, organ failure, coma and death. So, yes it can have long lasting effects.