Overview

A low sperm count means there is less sperm than is typical in fluid called semen that the penis releases during orgasm.

A low sperm count also is called oligospermia (ol-ih-go-SPUR-me-uh). A complete lack of sperm is called azoospermia (ay-zoh-uh-SPUR-me-uh). Your sperm count is considered lower than typical if you have fewer than 15 million sperm per milliliter of semen.

Having a low sperm count makes it less likely that one of your sperm will join with your partner's egg to start a pregnancy. If needed, there are treatments to help couples boost their chances of becoming pregnant.

Symptoms

The main symptom of a low sperm count is not being able to start a pregnancy. There might be no other clear symptoms.

In some people, an underlying health condition causes a low sperm count along with other symptoms. Depending on the condition, these other symptoms can include:

  • Trouble with sexual function — for example, some people have low sex drive. Others have trouble getting or keeping an erection that's firm enough for sex, also called erectile dysfunction.
  • Pain, swelling or a lump in the testicle area.
  • Less facial or body hair or other symptoms of a chromosome or hormone condition.

When to see a doctor

See a healthcare professional if you and your partner haven't been able to become pregnant after a year of regular sex without using birth control. This is how the condition known as infertility is defined. Get a healthcare checkup sooner if you have any of the following:

  • Erection or ejaculation concerns, low sex drive, or other troubles having sex.
  • Pain, discomfort, a lump or swelling in the testicle area.
  • A history of testicle, prostate or sexual problems.
  • Groin, testicle, penis or scrotum surgery.

Causes

For the body to make sperm, the testicles and certain organs in the brain that produce hormones need to work properly. Once sperm are made in the testicles, sperm travel in delicate tubes until they mix with semen. Then semen is released from the penis, usually during an orgasm. Issues with any of these systems can lower the number of sperm in semen.

When sperm's movement or shape is irregular, that also can lessen fertility.

Still, the cause of low sperm count often can't be found.

Medical causes

Low sperm count can be caused by health conditions such as:

  • Varicocele. A varicocele (VAR-ih-koe-seel) is a swelling of the veins that drain the testicle. It's a common cause of male infertility. It can lower sperm count and quality. For some people, surgery to fix a varicocele can improve sperm count, movement and shape. It's not clear exactly why varicoceles cause infertility, but they might have an effect on the temperature in the testicles.
  • Infection. Some infections can impact sperm health or the body's ability to make sperm. Certain repeated infections also can cause scarring that blocks the passage of sperm. Sexually transmitted infections such as gonorrhea or HIV can affect sperm count and fertility as well. So can infections from viruses, bacteria, or fungi that cause swelling of one or both testicles, or swelling of the coiled tube at the back of the testicle known as the epididymis. Most infections get better without causing any long-term issues. But some infections can cause lasting damage to the testicles. Still, healthcare professionals may be able to collect sperm as part of certain fertility treatments.

  • Trouble with ejaculation. Ejaculation is the release of semen from the penis. It usually happens during orgasm. If semen enters the bladder during orgasm instead of leaving through the tip of the penis, that's called retrograde ejaculation. Various health conditions and certain types of surgery can cause retrograde ejaculation or complete lack of ejaculation. These include diabetes, spinal injuries, and surgery of the bladder, prostate or urethra.

    Certain medicines also can affect ejaculation. These include blood pressure medicines known as alpha blockers. Some ejaculation issues can be treated. Others are lifelong. Often, sperm can still be collected directly from the testicles as part of certain fertility treatments.

  • Tumors. Cancers and tumors that aren't cancer both can affect the male reproductive organs directly. They also can affect these organs through the glands that release hormones related to reproduction, such as the pituitary gland. Surgery, radiation or chemotherapy to treat tumors in other areas of the body also can affect the body's ability to make sperm.
  • Undescended testicles. During pregnancy, one or both of an unborn baby's testicles sometimes don't drop down into the scrotum. The scrotum is the sac that usually contains the testicles. Lower fertility is more likely in adults who were born with this condition.
  • Hormone levels that become out of balance. A part of the brain called the hypothalamus and a gland at the base of the brain called the pituitary gland make hormones that are needed to create sperm. The testicles make hormones needed to make sperm as well. Changes in the levels of these hormones may mean that the body is having trouble making sperm. Changes in the levels of hormones that thyroid and adrenal glands make also may affect sperm count.
  • Changes in the tubes that carry sperm. Various tubes in the body carry sperm. These tubes can be blocked due to various causes. Causes can include an injury from surgery, past infections and trauma. Conditions such as cystic fibrosis also can cause certain tubes not to develop or to form in irregular ways. A blockage can happen at any level, including within the testicle or in the tubes that drain the testicle.
  • Genetic conditions. Some genetic changes passed from parent to child cause the male reproductive organs to develop in irregular ways. For instance, a condition called Klinefelter syndrome can cause the body to make less sperm. Other genetic conditions linked with infertility include cystic fibrosis, Kallmann syndrome and Kartagener's syndrome.

Some medical treatments also can cause a low sperm count, such as:

  • Certain medicines. Medicines that can cause the body to make less sperm include some treatments for arthritis, depression, anxiety, low testosterone levels, digestive trouble, infections, high blood pressure and cancer.
  • Prior surgeries. Certain surgeries may prevent you from having sperm in your semen. These surgeries include vasectomy, inguinal hernia repairs, surgeries of the scrotum or testicles, prostate surgeries, and large abdominal surgeries performed for testicular and rectal cancers. Often, surgery can be done to reverse the blockages that a past surgery caused. Or surgery can help retrieve sperm directly from the testicles and the coiled tube called the epididymis that's attached to each testicle.

Causes in a person's surroundings

Sperm count or function can be affected by being exposed to too much of the following:

  • Industrial chemicals. Long-term exposure to insecticides, pesticides and organic solvents may play a part in low sperm counts.
  • Heavy metals. Exposure to lead or other heavy metals can cause infertility.
  • Radiation or X-rays. Exposure to radiation can cause the body to make less sperm. It can take years for the body to make typical amounts of sperm after this exposure. With high doses of radiation, the body might make less sperm than usual for life.
  • Too much heat on the scrotum. Overheating the scrotum can affect sperm count and function.

Health, lifestyle and other causes

Other causes of low sperm count include:

  • Drug use. Anabolic steroids taken to boost muscle strength and growth can cause the body to make less sperm. Use of cocaine or marijuana might lower the number and quality of sperm as well.
  • Alcohol use. Heavy or ongoing alcohol use can lower testosterone levels and cause the body to make less sperm.
  • Tobacco smoking. People who smoke might have a lower sperm count than people who don't smoke.
  • Emotional stress. Long-term emotional stress, including stress over fertility issues, may affect semen quality.
  • Weight. Obesity may directly impact sperm. Or it may cause hormone changes that lessen fertility.
  • Sperm testing issues. A sperm count can appear lower than it really is due to various testing issues. For instance, a sperm sample may be taken too soon after your last ejaculation. Or the sample could be taken too soon after an illness or stressful event. Sperm count also can appear low if the sample doesn't contain all of the semen your penis released because some was spilled during collection. For this reason, results usually are based on a few samples taken over time.

Risk factors

Many risk factors are linked with low sperm count and other issues that can cause low sperm count.

Some risk factors are lifestyle choices, including:

  • Smoking tobacco.
  • Drinking alcohol.
  • Using certain illicit drugs.

Some health conditions can be risk factors, such as:

  • Being overweight.
  • Being very stressed.
  • Having certain past or present infections.
  • Having had trauma to the testicles.
  • Being born with a fertility disorder or having a blood relative with a fertility disorder.
  • Having certain health conditions, including tumors and long-term illnesses.
  • Having a history of undescended testicles.

Some treatments for health conditions also can be risk factors, including:

  • Cancer treatments, such as radiation.
  • Certain medicines.
  • Vasectomy or major abdominal or pelvic surgery.

Some things in a person's environment also may raise the risk of a low sperm count. These include being exposed to toxins.

Complications

Infertility caused by low sperm count can be stressful for both you and your partner. Complications can include:

  • Surgery or other treatments for an underlying cause of low sperm count.
  • Expensive and involved fertility treatments such as in vitro fertilization (IVF).
  • Stress from not being able to start a pregnancy.

Prevention

To protect your fertility, try to stay away from known factors that can affect sperm count and quality. Take these steps:

  • Don't smoke.
  • Limit alcohol or don't drink it.
  • Don't use illicit drugs.
  • Talk with your healthcare professional to find out whether any medicines you take can affect sperm count.
  • Stay at a healthy weight.
  • Try not to become overheated.
  • Manage stress.
  • Do what you can to avoid exposure to pesticides, heavy metals and other toxins.
By Mayo Clinic Staff