Low Sperm Count: Causes, Symptoms and Treatment

Low sperm count, also called oligospermia, means semen contains fewer than 15 million sperm per millilitre, or fewer than 39 million in total. It can make conception harder, but many men with a low count still conceive naturally. A semen analysis is the main test, and treatment depends on the underlying cause.

What does low sperm count mean?

Low sperm count means there are fewer sperm than usual in semen, the fluid released during orgasm. The medical term is oligospermia, while a complete absence of sperm is called azoospermia. According to the Mayo Clinic, a count is lower than typical if there are fewer than 15 million sperm per millilitre of semen (milliliter in the US), or fewer than 39 million in the whole sample.

The Cleveland Clinic notes that a typical count ranges from 15 million to over 200 million sperm per millilitre, and a count below 5 million per millilitre may be described as severe oligospermia.

Count is only part of the picture: fertility also depends on how well sperm move (motility) and on their shape (morphology). Many people with low counts conceive naturally, while some with typical counts do not.

What are the signs and symptoms?

In most cases, low sperm count causes no symptoms at all. The main sign is usually difficulty conceiving after a year of regular sex without contraception, and many men only discover it through fertility tests, as NHS 111 Wales explains.

Some men notice symptoms linked to the underlying cause instead:

• Problems with sexual function, such as a low sex drive or difficulty getting or keeping an erection
• Pain, swelling or a lump in the testicle area
• Less facial or body hair, or other signs of a hormone or chromosome condition

None of these signs confirms a low count on its own — only a semen analysis can do that — so treat them as a reason to talk to a doctor.

What causes a low sperm count?

Making sperm needs the testicles, the brain structures that release reproductive hormones, and the tubes that carry sperm to all work properly. A problem at any stage can lower the count, and often no cause is found. Causes fall into three groups: medical, environmental and lifestyle.

Medical causes

Several conditions and treatments can reduce sperm production or block sperm reaching semen:

• Varicocele. Swollen veins draining the testicle, a common cause of male infertility that can lower sperm count and quality. About 4 out of 10 men with low sperm counts have one, according to the Cleveland Clinic.
• Infection. Some infections affect sperm production or health, and repeated infections can scar and block the sperm-carrying tubes. Sexually transmitted infections such as gonorrhoea or HIV can also play a part.
• Problems with ejaculation. In retrograde ejaculation, semen enters the bladder during orgasm instead of leaving the penis — a possible result of diabetes, spinal injury or surgery on the bladder, prostate or urethra.
• Hormone imbalance. The hypothalamus and pituitary gland in the brain, with the testicles, make the hormones needed to create sperm, and changes in their levels can reduce production.
• Blockages. Sperm-carrying tubes can be blocked by injury, past infection or surgery, and cystic fibrosis can cause some of them not to develop normally.
• Undescended testicles. If a testicle did not drop into the scrotum before birth, adult fertility is more likely to be reduced.
• Genetic conditions. Klinefelter syndrome, cystic fibrosis, Kallmann syndrome and Kartagener’s syndrome can affect sperm production or reproductive development.
• Cancer and its treatment. Tumours can affect the reproductive organs or hormone glands, and surgery, radiotherapy or chemotherapy can reduce production.
• Certain medicines. Some treatments for arthritis, depression, anxiety, low testosterone, digestive problems, infections, high blood pressure and cancer can lower sperm production. Never stop one without talking to a doctor or pharmacist first.
• Previous surgery. Vasectomy, hernia repair and surgery on the scrotum, testicles or prostate can prevent sperm appearing in semen.

Environmental causes

Certain substances and conditions can also affect sperm count:

• Industrial chemicals. Long-term exposure to pesticides, herbicides, organic solvents and painting materials may play a part in low counts.
• Heavy metals. Exposure to lead, arsenic, cadmium or mercury can affect fertility.
• Radiation. Exposure to radiation or X-rays can reduce sperm production, and recovery can take years after high doses.
• Heat. The testicles work best slightly cooler than body temperature, so overheating the scrotum — for example, in a hot tub — can affect sperm production.

Lifestyle and other causes

• Anabolic steroids and recreational drugs. Steroids taken to boost muscle growth reduce sperm production, and cocaine or marijuana use may lower sperm number and quality.
• Alcohol. Heavy or ongoing drinking can lower testosterone levels and sperm production.
• Smoking. People who smoke may have a lower sperm count than non-smokers.
• Weight. Obesity may affect sperm directly or through hormone changes.
• Stress. Long-term emotional stress, including stress about fertility itself, may affect semen quality.

How is low sperm count diagnosed?

The main test is a semen analysis: a sample collected at a clinic is examined under a microscope to count the sperm and check their movement and shape. The Mayo Clinic advises no sex or masturbation for 2 to 7 days before the sample, and no lubricants, as these can affect sperm movement.

Counts vary from day to day, so a single result is rarely the final word. The Mayo Clinic suggests a second sample at least two weeks after the first, while the NHS advises repeating the test usually around 3 months later if a problem is found. The wait has a reason: new sperm take about 42 to 76 days to mature, so a semen analysis reflects your health over the past three months, and lifestyle changes will not show in results for several months.

The UK’s NICE fertility guideline compares results with World Health Organization (WHO) reference values — a benchmark for doctors, not a pass-or-fail score:

What is measured	WHO reference value
Sperm concentration	16 million per millilitre or more
Total sperm number	39 million per ejaculate or more
Total motility	42% or more moving
Progressive motility	30% or more moving forwards
Vitality	54% or more live sperm
Normal forms (morphology)	4% or more

If two or more analyses are abnormal, further tests may follow: a physical examination, blood tests for hormones such as testosterone, a scrotal ultrasound scan, a urine test after ejaculation to check for retrograde ejaculation, and genetic tests if the count is extremely low. Your GP can arrange the first tests and refer you to a specialist.

Treatment and steps that may help

Treatment depends on the cause, and there is no single option that suits everyone. The first step is usually to look for a treatable cause:

• Surgery. A varicocele can often be repaired, as can a blocked vas deferens (the tube that carries sperm), and past vasectomies can sometimes be reversed. If no sperm are present in semen, sperm can often be collected directly from the testicles or epididymis.
• Treating infections. A reproductive tract infection can often be treated with antibiotics prescribed by a doctor.
• Reviewing medicines. If a medicine may be affecting sperm production, a doctor may suggest an alternative. Do not stop or change a prescribed medicine on your own.
• Assisted reproductive technology (ART). Treatments such as in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) may help couples who have not conceived. With ICSI, a single sperm is injected directly into an egg in a laboratory. Donor sperm is another option if the count is very low.

Everyday steps may also support sperm health. The NHS recommends drinking no more than 14 units of alcohol a week, stopping smoking, losing weight if you are overweight, wearing loose-fitting underwear, and avoiding recreational drugs such as anabolic steroids or cocaine. The Mayo Clinic adds managing stress and avoiding overheating the testicles. Because sperm take weeks to mature, a repeat test after about three months is usually needed before any improvement shows up.

Can you still conceive with a low sperm count?

Yes, often. A low count lowers the odds that a sperm will reach and fertilise an egg, but it does not make pregnancy impossible, and many men with low counts conceive naturally by giving it more time. The NHS advises couples trying for a baby to have sex every 2 to 3 days without contraception, which keeps fresh sperm available around ovulation. If pregnancy has not happened after a year, tests for both partners can help, and IVF and ICSI give many couples a real chance.

When to see a doctor

See a GP if you and your partner have had regular sex without contraception for over 1 year (or 6 months if your partner is 36 or over) without a pregnancy. Your GP can arrange fertility tests for both of you and refer you to a specialist if needed.

Get checked sooner if you notice any of the following:

• Problems with erections or ejaculation, a 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, or surgery in that area
• A known condition that could affect fertility, such as an undescended testicle

Low sperm count is not an emergency in itself, but pain or sudden swelling in the testicles needs a prompt check. In an emergency call 911 (US), 999 (UK) or 112 (EU).

Finding out about a low sperm count can be stressful. A GP or fertility specialist can explain your results. A low count is a starting point for investigation, not a final answer.