RN
Most sex misinformation is not invented maliciously. It gets assembled out of half-remembered classroom material, a friend's confident anecdote, and whatever the culture around you found too awkward to correct. Then it sits there for twenty years unchallenged, because nobody wants to be the person who admits they were not sure.
So here are six beliefs that come up constantly, each one held against what public-health bodies and published research actually say. Where the evidence is strong, that is stated plainly. Where it is an association rather than a proven cause, that is stated too — the difference matters more than any individual finding.
"Infections track poverty"
They track exposure. A pathogen has no way of reading a bank balance, and every plausible mechanism by which money would protect somebody runs through behaviour and access to care rather than through any biological shield.
What money does buy is testing, treatment and the confidence to ask for both. That produces a real difference in outcomes, and it is easy to mistake for a difference in susceptibility. It is not the same thing, and treating your income bracket as a risk assessment is how people end up not testing.
"Once you have had something, you cannot get it again"
This is the one that causes actual harm, because it produces a reasoned decision to skip precautions.
The intuition comes from childhood viral illnesses, where a single infection really does leave durable protection. Most sexually transmitted infections do not behave that way at all. Bacterial infections in particular leave no meaningful immunity — clearing one with antibiotics returns you to exactly the same susceptibility you had beforehand.
The clinical guidance reflects this directly. CDC advice is to retest around three months after treatment for chlamydia, gonorrhoea or trichomoniasis, and the reason that recommendation exists is that repeat infection is common enough to plan around rather than a rare surprise.
Hepatitis is the partial exception people have half-heard. Recovering from hepatitis A does leave lasting antibody protection, and hepatitis B is both vaccine-preventable and usually cleared with immunity in adults. Those are specific facts about two specific viruses. They generalise to nothing else on the list.
"Nobody gets pregnant the first time"
There is no mechanism here at all. This is folklore that survives because it is useful to whoever is repeating it.
Conception depends on where somebody is in their cycle, not on how many previous times they have had sex — and cycles are irregular enough, particularly in the years when this myth circulates most, that "safe" timing is a much weaker guarantee than people treat it as. Sperm also remain viable inside the body for several days, which widens the window well past the day itself.
If you want a number to hold onto, hold onto this one instead: the only useful figure is the effectiveness rate of whatever method you are actually using.
"Washing afterwards works"
It does not, and the reason is timing. Semen enters the upper reproductive tract quickly, and by the time anyone is in a position to wash, the part that matters is already past anything external water can reach.
Douching specifically is worse than merely ineffective. The Office on Women's Health and the wider literature link it to disrupted vaginal flora and elevated rates of infection, including pelvic inflammatory disease — plausibly because flushing pushes bacteria upward into a tract that is normally kept clear. It is one of the few hygiene practices where the recommendation is a flat "don't".
Pre-ejaculate is worth mentioning in the same breath, since it can carry sperm and arrives before anybody has decided anything.
"Two condoms are twice as safe"
Reasonable-sounding and wrong. CDC guidance is explicit that only one should be used at a time.
Two latex surfaces moving against each other generate friction that neither was designed to take. The failure modes are the obvious ones — tearing, or an external condom being dragged out of position, or an internal one pushed further in — and all of them leave you worse off than the single condom you started with. Doubling up on the same layer is not redundancy. Combining two different methods, such as a barrier plus hormonal contraception, is.
"Frequent masturbation damages you"
The historical version of this claim was invented whole, and its modern descendants have not fared much better under study.
The most-cited work here points the other way. The Health Professionals Follow-up Study, which tracked tens of thousands of men prospectively and was updated in European Urology in 2016, found men reporting 21 or more ejaculations a month had roughly a 31% lower rate of prostate cancer than men in the 4–7 range. That is a large cohort and a well-conducted one — and it is still observational, which means it establishes an association and cannot on its own establish that the ejaculating caused the difference. Report it as what it is.
The related claim about pornography rotting the brain deserves the same care in the opposite direction. ICD-11 does contain a relevant diagnosis, compulsive sexual behaviour disorder, and it is classified as an impulse-control disorder rather than as an addiction — a distinction the WHO made deliberately, and one still argued over in the literature. So the honest position is neither "porn addiction is a proven neurological condition" nor "there is no such thing as a problem here". Compulsive sexual behaviour that causes real distress or wrecks somebody's functioning is recognised, is treatable, and is not the same thing as ordinary use.
What to do with this
The pattern running through all six is that the confident version of the claim is usually the wrong one, in either direction. "Definitely safe" and "definitely harmful" are both doing more work than the evidence supports.
None of this is medical advice, and it is not calibrated to you. Testing, contraception and anything persistent or painful are all questions for a clinician, who can account for your history in a way a general article structurally cannot. The value in knowing which of these are myths is mainly that it stops a false belief from making the decision for you before you get there.