Gel, sex, swimming pools: myths?

You’re 23, your temples are going back a little, and you’re typing your question into Google at one in the morning. Ten minutes later you have your list of culprits: your hair gel, Thursday’s swim, your scooter helmet, your sex life and, of course, “too much testosterone”. Some of the advice contradicts itself, some of it makes you feel guilty. Hardly any of it cites a study.

We went through them one by one. Most don’t hold up. Only one, the one people mention least, has real evidence behind it.

Where these ideas come from

A team of Irish dermatologists set out to gauge the problem. In 2024, they went through the first ten pages of Google results on hair loss and misinformation, then searched hashtags on X, Facebook, Instagram and TikTok¹. They found three families of misinformation: false causes, unfounded criticism of recognised treatments, and “natural” remedies with no evidence¹. Those remedies, from rosemary oil to onion juice, have an article of their own: viral hair loss tips, put to the test.

Among the false causes: wearing hats, some hair care habits such as brushing or washing, and certain sexual practices¹. The authors acknowledge their limits: it’s impossible to read everything on the internet, and they only looked at English-language content¹. It’s a qualitative snapshot, not a count. It’s enough to show that these ideas spread widely, and not on medical websites.

Does hair gel make you bald?

Not in the sense of pattern baldness: that happens in the follicle, the root that makes the hair under the skin, driven by genes and hormones⁴. Gel stays on the hair shaft. That doesn’t make it entirely harmless, though.

The American Academy of Dermatology (AAD) advises cutting back on “long-lasting hold” styling products. The main problem is the comb: using a comb to style your hair after applying the product can break the hair and, over time, lead to hair loss². Its simplest advice: choose a hairstyle that doesn’t need a strong-hold product³.

In other words, gel worked in with your fingers and washed out at night won’t push your hairline back. Hair broken by a comb every morning, for years, eventually shows. For the rest of your routine, hairdryer included, we’ve put together four gentler styling habits.

Sex and masturbation

It’s the most embarrassing myth, and one of the most persistent among young men. The Irish team found it mainly on websites with religious affiliations, which claim that hair loss comes from certain sexual practices¹. They class it among the false causes.

Dermatologists explain hair loss very differently. The French Society of Dermatology (SFD) puts pattern baldness down to a sensitivity of the hair to certain hormones, largely inherited⁷. DermNet, the New Zealand dermatology reference, describes a genetic sensitivity to DHT⁴. Neither mentions how often you have sex or masturbate.

The reasoning that circulates usually goes through testosterone. So that’s where to look.

Too much testosterone?

The idea is simple: a bald man must have more male hormones. In reality, what matters is how the follicles respond. DermNet describes male pattern hair loss as a genetically determined sensitivity to the effects of DHT (dihydrotestosterone), a hormone made from testosterone. DHT is believed to shorten the hair’s growth phase. The genes involved come from both your mother and your father⁴.

When testosterone is measured in the blood, the results don’t back up the myth. A Mexican study compared 80 men aged 18 to 35 with clear pattern hair loss to 80 men of the same age and weight without it. Free testosterone was higher in the men without hair loss⁵. The study was run in a single hospital and was mainly looking for a link with insulin resistance, but the result clearly contradicts the cliché.

Another study, in the United States, of 315 older men found the opposite, with a small gap: 16.5 pg/ml of free testosterone in men balding on the crown, against 14.8 pg/ml in those with little or no hair loss⁶. Taken together, these contradictory results show that testosterone levels don’t sort bald men from the rest. It’s the follicles, and so heredity, from your mother’s and your father’s side, that make the difference.

Motorbike and hard-hat helmets

Motorcyclists, builders, cyclists, firefighters: lots of men wear a helmet for hours a day and worry about it. The SFD is unambiguous: regularly wearing a helmet or a cap doesn’t make pattern hair loss worse⁷. The Irish dermatologists also list headwear among the false causes, with no evidence behind it¹.

If you’re starting to thin, a cap actually protects your scalp from sunburn⁷. For the myths that concern everyone, like cutting at the full moon or 100 brush strokes, we’ve sorted fact from fiction in caps, haircuts, the full moon: true or false.

Swimming pool chlorine

The pool does damage your hair, but the shaft, not the root. A Japanese team examined 67 swimmers from the national team and 54 people of the same age who didn’t swim⁸.

Under the microscope, the swimmers’ discoloured hair had lost its protective outer layer, the cuticle. The researchers put this mainly down to friction with the water, and to the pool’s hypochlorous acid, which gets into the hair⁸. On the other hand, a test on the hair bulb, the living part under the skin, showed no difference between swimmers and non-swimmers⁸. The study is small and looks at athletes who spend hours in the water; it didn’t measure hair loss.

If you swim often, the AAD recommends washing your hair with shampoo and conditioner after swimming, then drying it promptly³. That’s what protects the shaft. Your hairline doesn’t depend on it.

Smoking is no myth

After debunking so many myths, you might think nothing you do matters. That’s not quite true. A 2024 review brought together 65 studies on early-onset pattern hair loss, most of them in men. The risk factors it found include a family history, smoking and an unhealthy diet⁹.

The authors are cautious: they didn’t assess the quality of the studies, only included articles in English, and definitions varied from one study to the next⁹. It’s an association, not proof that cigarettes cause baldness. But it’s already more solid than gel or helmets. If you have a receding hairline at 20, that’s one more reason to quit.

Tracking what’s really happening

These myths all have the same effect: they make you change a habit, then watch the mirror to see if it worked. You stop using gel, you give up swimming, and every morning you think you see progress or a disaster. The light and the angle are enough to fool you.

To track your temples and crown, you need comparable photos: same room, same distance, dry hair, one shot of your hairline and one of your crown. With Calvap, the previous photo shows as a see-through overlay while you frame the shot, and your pictures line up week after week on a timeline. We’ve explained why to track both your temples and your crown.

After a few months, you know whether your hairline is moving or not. And if you see a doctor, they can suggest a treatment based on dated photos rather than an impression.