Precum, short for pre-ejaculate, is a clear fluid that comes out of the penis during sexual arousal, before ejaculation happens. It’s produced by small glands near the base of the penis and released involuntarily, meaning you can’t control when or how much comes out. The amount varies from person to person, ranging from barely noticeable to up to 4 milliliters.
Where It Comes From
Precum is produced by a pair of pea-sized glands called the Cowper’s glands (also called bulbourethral glands), located just below the prostate. When arousal triggers signals through the nervous system, these glands secrete fluid into the urethra, the same tube that carries both urine and semen out of the body.
The release is controlled by involuntary nerve fibers, the same type that regulate other automatic body processes like digestion and heart rate. This means there’s no way to consciously stop it, start it, or control how much is produced. Some people produce a large amount, others produce very little, and both are completely normal.
What Precum Actually Does
Precum serves a specific biological purpose: it prepares the urethra for ejaculation. Urine is acidic, and traces of it remain in the urethra between trips to the bathroom. Since sperm are sensitive to acid, precum acts as a neutralizing rinse, creating a more hospitable path before semen travels through. It also provides some natural lubrication during sex.
The fluid itself is mostly water, along with enzymes and mucus. It looks clear or slightly translucent and has a slippery consistency, noticeably different from the thicker, white appearance of semen.
Can Precum Cause Pregnancy?
This is the question most people are really asking, and the short answer is yes, it’s possible. Precum on its own, as produced by the Cowper’s glands, does not contain sperm. However, sperm from a previous ejaculation can linger in the urethra and get picked up by precum as it passes through. Studies examining pre-ejaculatory fluid have found that some samples contain motile (actively swimming) sperm, while others contain none. The difference likely comes down to whether sperm were still present in the urethra from an earlier ejaculation.
This is why the withdrawal method (pulling out before ejaculation) carries a real pregnancy risk. With perfect use every single time, the failure rate is about 4% per year, which is close to the 3% rate for condoms used perfectly. But in real-world use, where timing mistakes happen, about 18% of couples relying on withdrawal experience a pregnancy within the first year. That’s nearly identical to the 17% typical-use failure rate for condoms.
Urinating between ejaculations can help flush residual sperm from the urethra, which may reduce the chance that precum picks up live sperm. But this isn’t a reliable contraceptive strategy on its own.
Can Precum Transmit STIs?
Yes. Sexually transmitted infections like HIV, gonorrhea, and chlamydia can be present in pre-ejaculatory fluid. The risk exists even without full ejaculation. For people concerned about STI transmission, barrier methods like condoms are effective whether or not ejaculation occurs, because they also cover the period when precum is being released.
How Much Is Normal?
There’s a wide range. Some people barely notice any fluid, while others produce enough that it soaks through clothing during prolonged arousal. Research has documented volumes up to 4 milliliters, roughly a small teaspoon, though most people produce less than that. The amount can also vary from one sexual encounter to the next based on how long arousal lasts and individual differences in gland activity.
Producing a lot of precum isn’t a medical concern, and neither is producing almost none. If the amount is bothersome during daily life, especially if it happens frequently outside of sexual situations, that’s worth mentioning to a doctor, since it could occasionally signal an issue with the prostate or urethra. But during arousal, virtually any amount falls within the normal range.