Why does semen smell like that?

Semen, or seminal fluid, doesn’t always smell the same. Semen contains numerous substances that influence its smell, and your individual diet, hygiene, and sex life all play a part.

Certain foods can give it a sweet scent (and taste!). But eating or drinking acidic substances can make your semen smell foul. Some infections and conditions can influence its odor, too.

Read on to learn why semen has such a distinct scent, when you should see your doctor about the smell, and how to improve your overall odor.

If it smells like ammonia, bleach, or chlorine

Semen normally smells like ammonia, bleach, or chlorine.

Semen is about 1 percent sperm and 99 percent other compounds, enzymes, proteins, and minerals.

Many of these substances are alkaline. This means that they’re above a 7 on the pH scale, which is measured from 0 (highly acidic) to 14 (highly alkaline).

Some alkaline substances in semen include:

  • magnesium
  • calcium
  • copper
  • zinc
  • sulfur

Overall, seminal fluid typically leans slightly alkaline. Anything between 7.2 and 8.0 is considered a healthy pH level. When your body’s pH levels are balanced, semen should smell like ammonia, bleach, or other alkaline substances.

You might notice variations in this scent, especially after you have sex. The vagina leans toward the acidic side, with a typical pH level between 3.8 and 4.5. This acidic environment can interact with the substances in semen and temporarily alter the smell.

If it smells like fish or rotten eggs, or is generally foul

Fishy, rotten, or foul-smelling semen isn’t normal.

Eating certain foods — like asparagus, meats, and garlic — or drinking a lot of caffeine or alcohol can make your semen smell pungent. Try limiting these foods to see if your semen smell returns to normal after a few days. If so, there’s nothing to be concerned about.

If the smell persists, it could be a sign of a sexually transmitted infection (STI) or other underlying condition, such as:

  • Trichomoniasis. This bacterial infection can cause itching and burning, as well as smelly penile discharge.
  • Gonorrhea. This bacterial infection can cause burning when you urinate, testicle swelling, and white, green, or yellow penile discharge.
  • Prostatitis. This refers to inflammation of the prostate gland. It’s usually caused by a bacterial infection. Symptoms include pain when urinating, cloudy or bloody urine, pain during ejaculation, or having to urinate more often than usual.

See your doctor for diagnosis if you notice these symptoms along with foul-smelling semen.

So what exactly does semen smell like?

Curious to know when semen smells like? Take a whiff of Pyrus calleryana, a pear tree found throughout North America.

As Vice reports, it’s well-known as the “semen tree.” When its flowers bloom during the spring, large amounts of organic chemicals called amines are released into the air.

These are the same chemicals found in body odor, fish, and, of course, semen. This pervasive scent is like that of semen — or as one Urban Dictionary user puts it, “used sex rags.”

What can affect the scent?

Many different factors influence your body’s chemical balance, as well as the concentration of bacteria and other substances that mingle with semen and alter your scent.

Circumcision

If you’re uncircumcised, the concentration of sweat, skin oils, dead skin cells, bacteria, and smegma under your foreskin can all mix with your semen during ejaculation. This can change the way your semen smells.

If you’re circumcised, sweat and oils can still affect your scent, but they typically don’t build up to the same high concentrations. That’s because there’s nothing to trap these substances underneath the skin.

Dried sweat or urine

Sweat and urine contain high levels of sodium, an alkaline substance. The sodium left behind on your skin after sweat or urine dries can make your semen smell even more like bleach or chlorine if it gets mixed in.

Sweat and urine also contain numerous other substances that can react with the alkaline substances in semen. Chloride, potassium, and magnesium can all alter its scent.

Diet

What you eat and drink contains chemicals, nutrients, and other substances that can mix with your semen contents.

Some are thought to make your semen smell (and taste) sweeter, including:

  • fruits, such as pineapple, oranges, and papaya
  • some vegetables, such as broccoli, celery, and wheatgrass
  • “sweet” spices, such as nutmeg and cinnamon

Some are thought to make your semen more bitter, including:

  • caffeine
  • alcoholic drinks
  • cabbage
  • asparagus
  • leafy greens, such as spinach
  • meats
  • milk and other dairy products

Some of these foods are healthy, so don’t stop eating them altogether if you’re concerned about your semen smell. You can always add in more fruits and spices to try to keep things balanced.

Can you change the way semen smells?

Your diet, lifestyle, and hygiene can all affect semen smell. To help maintain its typical alkaline smell:

  • Bathe regularly. Always wash your penis and underneath the foreskin, if applicable.
  • Eat a healthy diet with plenty of fruits and vegetables.
  • Limit your caffeine and alcohol intake.
  • Use protection during sex.

See your doctor if you notice an unusual odor, especially if you’ve had sex with a new partner. Your doctor can determine the underlying cause and advise you on any next steps.