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The science behind "pilly willy": here's what recreational drugs can do to your sex life

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The (not so) hard science behind the ‘pilly willy’ and ‘whiskey dick’: some substances increase your desire to have sex, while removing your ability to do so.

The intentional, consensual act of having sex whilst under the influence of drugs such as MDMA, cocaine, cannabis and GHB is on the rise, particularly in the UK. There’s one simple explanation for it - some drugs can make you feel more sociable, more touchy-feely, happier and, well, up for ‘it’.

But aside from the well-known effects, both pleasant and unpleasant, one of the frustrating side-effects about some of those drugs in the short-term is how they can seemingly increase your desire to have sex while removing your ability to do so.

Terms like ‘pilly willy’ (the apparent shrinking of the penis on MDMA) and ‘whiskey dick’ (a flaccid, unresponsive member after a heavy night of drinking) are widely used. Jokey phrases, though, might make light of what can become persistent and emotionally troubling erectile problems from the misuse of drugs or alcohol.

The relationship between recreational drugs and ED is a complicated one

Exactly how drugs affect the penis, and their role in ED (erectile dysfunction), has not been widely researched (what with the obvious issue of it being legally problematic to test recreational drugs on humans, however willing subjects might be).

There is strong anecdotal evidence though, along with our thorough understanding of the physiology of the penis, to be able to point the finger at the worst substances for erectile health...


A powerful and addictive stimulant, with its use on the rise in the UK, cocaine raises your mood, your heartbeat, your body temperature and the speed at which you chat rubbish to strangers in bars. What it definitely won’t raise is your penis at the end of the night.  

The science on cocaine and erections...

Be it in your brain, your heart or your penis, cocaine causes the narrowing of blood vessels in the body, known as vasoconstriction. This is not good news for erections.

For your penis to become firm, blood needs to flow freely into the spongy tissue inside it. Any restriction of this blood flow reduces the likelihood of a healthy erection.

Long-term use of cocaine has been linked with permanent vascular damage that means potentially chronic erectile issues. It also paves the way for a whole host of other problems such as intracerebral hemorrhages and other things you’d never want to Google Image search, let alone have.


If we’re to believe the movies, MDMA is good for sex. And true, it’s known to lower inhibitions and increase feelings of intimacy, with users frequently reporting the desire to have sex. The bit Hollywood tends to leave out is that it also kicks into gear the part of the nervous system that causes your erection to fade away.

The science on MDMA and erections...

As covered in our Book of Erections, when activated, the sympathetic nervous system constricts blood flow to the penis, causing your erection to fade. This usually happens after ejaculation, can be triggered by stress, or in this case the trigger can be mimicked by a drug: MDMA.

Some male users mix MDMA with sildenafil (Viagra) or other ED medication to counteract these effects. This is, perhaps unsurprisingly, highly inadvisable.

It’s a cocktail that can result in dangerous adverse effects and more alarmingly, this kind of drug use is linked to high-risk sexual behaviours (such as unprotected sex and/or sex with multiple partners), and transmission of STIs including HIV and other blood-borne viruses.


Poppers have long been the dancefloor drug du jour for swathes of sex-positive British clubbers. For a group of substances so closely associated with getting down to it, poppers can have a surprisingly detrimental affect on your ability to get an erection.

The science on poppers and erections...

As with alcohol, poppers cause your blood pressure to drop. This leads to the relaxation of muscles all over your body, including muscles in the sphincter, and some less welcome side effects (headaches, dizziness and fainting). The change in blood pressure can also leave you struggling to get or maintain an erection.

Anabolic steroids

Roids, gear, pumpers, juice... The nicknames for anabolic steroids should really be enough to put you off taking them. It’s a prescription-only medicine that when abused — often for performance enhancement in sports or bodybuilding — can play havoc with your genitals.

The science on anabolic steroids and erections...

Atrophy (or shrinking) of the testicles is a common side effect of steroid abuse. This is caused by a condition called hypogonadism, which can cause the diminished production of the sex hormone testosterone in the gonads. While research is limited on exactly how a lack of it may affect ED, testosterone is thought to play a key role in healthy erectile function.


Alcohol is a lot of things. The nation’s favourite Friday night lubrication for one, it’s such an ingrained part of our culture that ‘pubs’ and ‘pints’ are just as British as Buckingham Palace and Big Ben. It’s also a major cause of ED.

The science on alcohol and erections...

Besides making your head feel like a coffin full of broken glass the next morning, excessive drinking can have short and long-term effects on erectile function.

A night of binge drinking (defined as more than 8 units in a single session for men, which equates to about 4 pints of beer) can result in a drop in blood pressure, resulting in insufficient hardness for penetrative sex. Although there’s plenty of other stuff you can be doing other than penetrative sex (we aren’t talking about board games) it can more than a bit frustrating.

And as for chronic alcohol abuse, it goes without saying that it’s clearly pretty bad full stop. One of the many long-term effects is damage to nerve function, which can cause a more permanent form of ED.

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Whether snorted, popped or injected, when misused this essential medical and veterinary drug can have some pretty dire consequences on the body. From kidney damage to ED, the list is long and doesn’t make for pleasant reading.  

The science on ketamine and erections…

A 2016 study found “a significant association between ketamine use and erectile dysfunction,” especially in long-term users. It’s thought this may be due to low nitric oxide levels and cell death in the spongy erectile tissue in the penis (corpus cavernosum).


Methamphetamine, or crystal meth, increases the amount of the natural chemical dopamine in the brain making users exhilarated, alert and awake. The risks though are immense, including severe depression, dental problems (AKA meth mouth) and psychosis. Perhaps unsurprisingly, it’s not great for your penis either.

The science on methamphetamine and erections…

Sexual aggression and compulsive sexual behaviors are common amongst male users, with many reportedly using sildenafil. This suggests that methamphetamine may cause erectile dysfunction or that the behaviours it promotes necessitates its use.

For example, a 2016 study found that methamphetamine facilitates “sexual intercourse which lasts for several hours” by “increasing sexual desire, reducing behavioral inhibition, increasing the duration of erections.”

Other drugs

Heroin - The prevalence of ED is high amongst opioid abusers but the physiology is not clear. You can read more here.

Psychedelics (LSD, DMT, magic mushrooms)  - There’s no clear link to sexual side effects.

GHB - Causing increased sexual arousal GHB is linked to increased frequency of unsafe sex practices. It may be no clear link to ED, but with a fine line between dose and overdose which can be fatal, it’s a highly dangerous drug.

Cannabis - There are a number of contradictory findings about the effects of cannabis on erections: the consensus is unclear (a bit like how your head feels when you’ve smoked it).

The numan take

Healthy erectile function relies on key systems in the body working perfectly and in unison. Recreational drugs can disrupt this finely tuned process, leading to erectile problems, while excessive use can lead to more chronic forms of ED.