We all know sexually transmitted infections (STIs) can seriously damage your health. From infertility to cancer, STIs are a serious public health concern.

We get asked a lot about the effect of STIs on all areas of health, especially reproductive health. While it’s common for many STIs to cause infertility, we specifically get asked whether an STI can affect a man’s sperm count.

In this blog, we’ll answer this vital question so you can protect your sexual health.

What are STIs?

STIs are infections that are primarily transmitted through sexual contact. This can include vaginal, anal, and oral sex, but also include skin-to-skin contact. Common STIs include:

These infections can affect both men and women, and they often don’t present noticeable symptoms. Many infections survive and thrive in infected people for weeks, months, or even years before they’re detected.

The impact of STIs on sperm count

Several STIs can affect your sperm count.

Here’s a closer look at how different STIs can influence sperm health:

Chlamydia and Gonorrhoea

Both Chlamydia and Gonorrhoea are common bacterial STIs that can seriously damage the male reproductive system.

During a Chlamydia or Gonorrhoea infection, bacteria infect the urethra and urinary tract, causing large amounts of inflammation. This inflammation can reach the testicles and epididymis, causing scarring and blockages. This can potentially damage the body’s ability to produce and transport sperm correctly.


Herpes Simplex Virus (HSV) infections may have an effect on your sperm count.

One study conducted on Iranian men found that HSV infections did correlate with reduced sperm counts in some men. Interestingly, a stronger correlation with reduced sperm counts was found with males infected with HSV 1, the virus that tends to cause cold sores. Another metanalysis conducted by other academics in Iran found that HSV can be a risk factor for reduced fertility and infertility in men, although more research is needed in this area.

Outside of reduced sperm counts, the sores produced by Herpes outbreaks can make it very painful to have sexual intercourse. The pain experienced during sex may make it less likely for infected people to carry out the sexual act successfully.


A Syphilis infection has four stages:

  • Primary stage: characterised by the appearance of a firm, round chancre where the infection entered the body – usually around the genitals.
  • Secondary stage: characterised by the appearance of skin rashes, lesions, fever, swollen lymph nodes, sores throat, weight loss, and fatigue.
  • Latent stage: where the infection doesn’t produce symptoms and lays dormant in the body.
  • Tertiary stage: where the infections, over a long period of time, damages internal organs including the brain, eyes, nerves, heart, liver, and bones.

During the Tertiary stage of a Syphilis infection, it’s possible for the epididymis to be damaged, increasing the potential to cause obstruction of the flow of sperm. Another condition called obliterative endarteritis can also occur during Tertiary Syphilis, leading to small, fibrotic testes.

What to do

Early detection and prompt treatment of STIs are key to preventing long-term damage to your reproductive health.

Regular testing

If you’re sexually active, get tested for STIs regularly, even if you don’t have any symptoms. Getting tested will give you a better view of your sexual health and allow you to take action if you need to.

Seek medical advice

Consult a healthcare professional who can provide guidance on your specific situation. Early diagnosis and treatment can significantly reduce the impact of STIs on your reproductive health.

Open communication

Discuss your diagnosis with your sexual partner(s) and any potential partners in the future. Honest conversations can help everyone involved make informed decisions about sexual health.

Fertility support

If you’re trying to conceive, consider consulting a fertility specialist who can provide guidance and options for increasing your chances of becoming a parent.

Final thoughts

While having an STI can lower sperm count and affect fertility, it’s not a life sentence. With early diagnosis, appropriate treatment, and responsible sexual health practices, you can minimise the impact of STIs on your reproductive health.

If you think you may have an STI, you can get tested with Better2Know. Our Sexual Health Advisors can help you find the right test and clinic for you.

Call the number above to speak to someone today.

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