According to a new study, abusing amphetamines is definitely looking like it has an effect on men’s sexual functions. It just isn’t clear exactly how the drugs are affecting them.

Amphetamines refer to a group of stimulant drugs, including the well-known methamphetamine, MDMA and Adderall. Though some can be used effectively in the treatment of ADHD and Narcolepsy, amphetamines also carry a high risk for addiction and abuse. Abuse of amphetamines has been known to cause various medical complications, but only rarely have studies focused on the effects they have on sexual functions. Amphetamines affect the central nervous system and have a neurotoxic effect on the brain — both of which play a part in controlling and facilitating sexual function.

Previous research has found that amphetamine abuse can cause a wide range of changes in sexual functions — subjects reported side effects that included enhanced sexual desire, spontaneous erections upon injection, delayed or multiple orgasms, reduced libido, impaired ejaculation, and difficulty achieving orgasm. Most past studies looking at the relationship between amphetamines and sex had a lot of limitations, including small case numbers and undesirable variables, such as participants using multiple drugs.

The most recent research on the subject, authored by Dr. Bang-Ping Jiann, aimed to more effectively evaluate the impact of amphetamines on male sexual functions. Though the study included more subjects (1,159) and a control group, it wasn’t exactly successful at narrowing down what specifically amphetamines do in regard to men’s sex lives.

Half of the users reported that amphetamines had no effect on their sexual functions. Among those who did report effects, the descriptions varied between positive consequences and negative ones, with effects such as reduced erectile rigidity, enhanced orgasmic intensity, and delayed ejaculation all cropping up. One condition did seem to be consistently associated with amphetamines, though: erectile dysfunction.

“Compared with 211 matched controls, amphetamine users were twice as likely to experience erectile dysfunction,” said Dr. Bang-Ping Jiann in a press release.

Another notable find was that the participants' frequency of use had some association with its impact on sexual function, while duration of use did not. Those participants who used most frequently were most likely to report an increase in positive sexual function rather than negative.

Results as a whole were disparate, though, and future research may be needed to accurately determine the effects of amphetamines on the sexual functions of men.

Source: Bang-Ping J. The Impact of Illicit Use Of Amphetamine On Male Sexual Functions. The Journal of Sexual Medicine. 2015.