Precum: what it is and what it carries

A clear drop made by two tiny glands, in amounts from none to plenty. Whether it carries sperm depends on which study you read, and they disagree

It shows up before anything else does, a clear drop at the tip that announces the evening is going well. Some men barely produce any, some leave a wet patch through their jeans. Precum, or pre-ejaculate if you are writing to a urologist, is the least studied fluid a cock makes, and the few studies that exist do not agree with each other.

Here is what it is, where it comes from, how much is normal, and the honest answer to the question everyone asks: does it carry sperm?

Where it comes from

Precum is made mostly by two pea-sized glands tucked under the prostate, the Cowper's glands, also called bulbourethral glands. Their short ducts open into the urethra, the same tube that carries urine and semen, and tiny glands lining the urethra add a little more. The result is clear, slippery and slightly alkaline.

Its job is housekeeping: it lubricates the way out and neutralises the inside of the tube before the main event. It plays almost no part in the main event itself: textbook figures put the Cowper's glands' share of a full ejaculation at under one per cent. The bulk of semen comes from elsewhere, the seminal vesicles and the prostate supplying nearly all of it between them, so precum is a side door, not a preview of the main event.

How much is normal

Anything from nothing to a lot. Some men never see a drop, others produce enough to drip. A short clinical paper on men who complained about very copious precum describes amounts that reportedly go above 5 ml, more than a typical full ejaculation, and treats it as a harmless nuisance rather than a disease.

How much you make has nothing to do with size, fitness or how good you are in bed. For many gay men a generous leaker is a bonus, free lube included. If yours is a nuisance, it is still normal.

Does it carry sperm?

This is the one question researchers have actually tried to answer, mostly because straight couples want to know whether pulling out works. Four small studies looked, and they came back with four different answers.

So the honest answer is: sometimes, in some men, and nobody can say exactly how often. The samples are tiny and the methods differ, from smears collected during foreplay to drops caught on a dish before orgasm. One detail from the British study is intriguing: men who had sperm in their precum had it every time, and men who did not, never did, across up to five samples each. It may be a personal trait rather than luck.

Look closer and the groups are not even comparable. The Israeli study, the one that found nothing, had twelve men: five referred for coming too fast, three because they leaked too much precum during foreplay, and four healthy volunteers. The Thai men smeared their precum on glass slides and then gave a semen sample after masturbating. The American pilot study, the most careful about counting, found that only seven of its 70 samples contained sperm in numbers its authors considered meaningful, while every full ejaculation in the study contained moving sperm.

Put together, the picture is reasonably clear even if the percentages are not. Precum carries far fewer sperm than semen, often none, and some men seem more likely than others to leak a few. Four studies with 105 men between them are not enough to say more, and anyone who quotes a single precise figure is choosing the study that suits him.

Precum and HIV

Infected cells have been found in the precum of HIV-positive men, so pulling out before the finish is not protection. What does protect: an HIV-positive partner on treatment with an undetectable viral load, which produced no linked transmissions in 782 gay couples having sex without condoms, the evidence behind U=U, and PrEP for HIV-negative men. Condoms and regular testing cover the other infections that neither of those stops.

Myths worth dropping

• Lots of precum means a big load. Different glands, different fluid. There is no evidence that one predicts the other.
• A dry tip means you are not turned on. Plenty of very aroused men produce almost nothing.

Precum is the opening act. For the headline show, see Ejaculation.