When MDMA is added to an erectile aid (such as a PDE5 inhibitor), it greatly increases heart and circulatory risks such as heart attack. Since PDE5 inhibitors work by vasodilation, headaches are a common side effect of PDE5 inhibitors alone. The combination of the two can also cause priapism, an erection that lasts more than four hours, which is a risk taken when any ED medication is used. Priapism is painful and can cause lasting damage to the penis. People using sextasy are also more likely to engage in unprotected sex with more partners due to the disorientation and skewed reality they experience; unprotected sex may lead to the spread sexually-transmitted infections, some of which are potentially fatal if left undiagnosed and treated. Additionally, other unknown and possibly dangerous chemicals or drugs may be present in the MDMA itself or in a mixture of the MDMA and the erectile aid, which may all be in the form of tablets, capsules, or loose powder.