Typically, semen has a faint smell caused by a mixture of chemicals, such as citric acid and calcium. Semen with an unusual smell, such as a strong, fishy odor, might be a sign of infection.
Although semen helps sperm reach the egg, sperm only makes up 1% of semen. The liquids that make up the other 99% of semen give it an odor. This article will discuss what semen typically smells like and what unusual smells might mean.
Semen typically smells like substances that have a similar pH level, which is a measure of how acidic a chemical is.
Normal semen is slightly alkaline, with a pH ranging from 7.2 to 7.8. This is a similar pH to that of blood, and slightly lower than seawater and baking soda. Some people report a stronger smell that is similar to bleach or ammonia, which is normal.
Other chemicals that are in semen can also influence its smell. For example, some people may notice a sugary smell because semen contains fructose, a sugar found in fruits. Semen also contains magnesium and calcium, which can give it a slightly metallic or salty smell.
Semen is primarily made up of water, so the smell is usually faint. Some people may not even notice a smell.
It is usual for the smell of semen to change.
Semen typically has a faint odor, and a change in smell could be down to a shift in perception. For example, someone could detect a sweeter smell from the fructose at one time and a more salty odor from the calcium another time.
Prolonged or significant changes in the smell of semen may point to an underlying medical condition, such as a sexually transmitted infection.
Some smells that could signal a problem include:
- Very strong smell: Bacteria and other germs can change the way semen smells. If semen has a foul and overpowering odor or gets worse with time, it may be a sign of an infection or sexually transmitted disease.
- Sweet smell: Normal semen can smell slightly sweet because of the fructose it contains. But semen that has a particularly sweet odor could be an early warning sign of diabetes. One old study suggests that men with diabetes may have more sugar into their semen, giving it a sweeter smell than usual.
- Fishy odor: A fishy odor is not normal. Fishy smelling semen may indicate a sexually transmitted infection.
When semen changes in smell, it can also taste differently. Changes in taste can be another sign of an underlying medical condition.
The smell of semen can change if it mixes with other substances, such as urine or sweat. It can also smell differently when it dries. Dried semen tends to have a stronger, more noticeable smell.
The pH of semen may affect how it smells, and if the pH changes, it can affect the smell. The prostate also adds an acidic fluid to the semen, which lowers its pH. Changes in prostate function may affect both the pH and odor of semen.
The vagina is also slightly acidic. When semen combines with vaginal fluids, the smell can also change.
There is currently no good quality research linking changes in diet to lasting changes in the way semen tastes or smells. But just as food can change the way a person’s sweat or skin smells, it can also temporarily change the smell of semen.
People who are concerned about the smell of their semen should avoid strong-smelling foods, such as fish. They should also avoid foods that change the smell or color of other bodily fluids, such as asparagus.
Everyone’s semen smells differently. Some people may even notice the smell changing over time or with shifts in diet, exercise, rest, and other lifestyle factors.
It is best to see a doctor if:
- semen suddenly smells foul
- semen smells very sweet
- there is blood in the semen
- ejaculation becomes painful
- urinary issues occur, such as incontinence or more frequent trips to the bathroom at night
- the genitals become itchy
- unusual discharge from the penis
- bumps develop on or around the genitals
It is useful to pay attention to the smell of semen. A 2015 study found that semen pH influences sperm health, which can affect fertility.
It is possible to promote semen and reproductive health by:
- eating a healthful, balanced diet
- avoiding foods or supplements that claim to improve semen smell or quality
- avoiding smoking and using recreational drugs
- moderating alcohol use.
- getting plenty of exercise
Semen has a faint smell that varies from person to person.
Lasting changes to the smell of semen can be a sign of an underlying medical condition. For example, a strong foul or fishy smell can be a sign of infection or a sexually transmitted condition. See a doctor if these changes occur.
Some things can change the smell of semen, such as when it mixes with urine. However, diet cannot change the smell of semen in any lasting way.