In 2018, social media was randomly ablaze with discussions about seasonal dick size.
"If you can't handle me at my winter penis, you sure as hell don't deserve me at my summer penis," wrote Twitter user @intothecrevasse, quote-tweeting an article that claimed the penis gets smaller during cold-weather months.
A few months earlier, MEL Magazine had printed a story about "the summer penis," exploring the theory that heat adds an extra inch or two to your penis. Despite what seems like a global obsession with dick size, there's apparently still a lot we don't know.
Perhaps surprisingly, it's not just the weather that causes these changes. You might not always notice them, but a handful of key factors can change the size––or, in some cases, the perceived size––of your johnson.
The key difference between actual and perceived shrinkage
The first factor to consider is your weight, although the science around this is arguably misleading.
In a 2021 study published in Andrologia, 4,685 Italian men measured their penis over the course of a year. In the study's abstract, researchers reported "the increase in BMI [body mass index] leads to a reduction in the length of the erect penis, as well as weight gain reduces the length of the flaccid penis."
However, it is extremely unlikely that these members are actually getting smaller. According to New York-based urologist David Schusterman, M.D., the most common reason the penis may appear bigger or smaller is as people gain or lose weight.
The key phrase here is "may appear." What's likely happening is that weight gain around the abdominal wall is making the pubic area fattier, and that extra fat is having a minor impact on the length measurement of the penis. Vijay Goli, M.D., a urologist at California-based Rise Medical, confirmed this theory.
"Some patients gain a large fat pad in their infrapubic area," he explained. "This fat pad will push over the penis, giving the appearance of a shorter penis."
The most common reason the penis may appear bigger or smaller is as people gain or lose weight.
The "winter penis" memes do have a point, though: Cold weather genuinely does make your genitals shrink.
"You can expect your penis to shrivel by about 50 percent in length and 20 to 30 percent in girth when you're exposed to any air temperature below 60 degrees," Schusterman confirmed. "It's all about blood flow. When exposed to the cold, blood vessels dilate, which limits blood flow to your penis."
As for summer penis, the jury is more or less still out. Doctors have conflicting opinions on the summer penis phenomenon, and the evidence most commonly cited in media reports is anecdotal and written by Reddit users.
Apparently, there is a condition called "summer penile syndrome," which sounds significantly less pleasurable. According to a 1998 study published in Pediatric Emergency Care, this "seasonal acute hypersensitivity" can result in a burning itch and decreased penile strength, particularly in children, and is usually attributed to insect bites.
So, yes, there is medical evidence of a summer penis. It's just not what you think.
Not all causes of penile shrinkage are seasonal
Those factors are environmental, but others are strictly medical, according to Josh Gonzalez, M.D., a board-certified urologist in Los Angeles who acts as resident sex advisor at Astroglide, a lubricant manufacturer based in California. He listed a handful of other reasons for dicks to decrease in size, including smoking, prostate surgery, cardiovascular disease and Peyronie's disease.
Age is next on the list.
"It's common for the penis and testicles to decrease with age," Gonzalez explained. "As we age, our cardiovascular system starts to decline, which can lead to diminished blood flow to the genitals. Poor blood flow over time causes atrophy or shrinkage of the testicles."
According to Goli, testicular injury can be responsible for testosterone-related shrinkage, too.
Research also shows that older men are more likely to be diagnosed with erectile dysfunction (ED). In a 2016 report published in the International Journal of Clinical Research, the prevalence of ED diagnosis or treatment increased from ages 18 to 29 (0.4 percent) to ages 60 to 69 (11.5 percent), and then decreased in the seventh (11 percent), eighth (4.6 percent) and ninth (0.9 percent) decades. However, ED was significantly more likely to occur in patients with other comorbidities, so aging alone is no guarantee you'll develop erectile dysfunction.
Gonzalez was also quick to point out testosterone also plays a role in this gradual decline of penis size.
"As people age, their testosterone decreases, which can, in turn, lead to the decreased size of their penis and testicles," he explained.
That's not to say testosterone injections can increase your penis size, however. Although testosterone causes clitoral enlargement (also known as bottom growth), there's no evidence to suggest it increases the size of cisgender penises, aside from occasional medical treatment for a micropenis.
The final reason your penis may fluctuate in size is backed by limited medical research. In 2004, a case report published in the International Journal of Clinical Practice described a phenomenon known as "whizz-dick." The researcher outlined the case of a patient "who described a koro-like syndrome related to amphetamine use; this consisted of a perception that his penis had reduced in size and was at risk of being sucked into his body." Amphetamine users at a drug rehabilitation clinic reported similar cases of "whizz-dick," describing it as "temporary penile shrinkage," according to the case report. Koro is classified as a type of obsessive-compulsive disorder.
There's been little widely publicized follow-up research, but it's known among recreational drug users that some substances can absolutely impact the size of your genitals. MDMA, cocaine and even prescribed stimulants such as Adderall can cause temporary penile shrinkage, because they restrict blood flow through vasoconstriction, Gonzalez noted.
That's not all.
"Other prescription medications that can lead to shrinkage include some antidepressants, antipsychotics and even drugs used to treat prostate enlargement," he added.
Gonzo doctors on the r/drugs subreddit share similar stories of temporary shrinkage, with one describing his MDMA-influenced penis as looking "like an acorn—all head, no shaft."
These size fluctuations are almost always temporary, though, with the exception of those that come with age, and even that's often exaggerated.
Whether it's winter penis on your mind or drug-fueled shrinkage, it's likely your junk will return to its usual size sooner rather than later.