What is the worst effect of STI?

The worst effects of STIs come from infections that are left untreated. Most STIs are easily dealt with if caught early. The problems happen when people don't get tested and don't get treated.

Untreated chlamydia or gonorrhoea can lead to pelvic inflammatory disease (PID) in women, which can cause chronic pain and infertility. In men, untreated infections can cause painful swelling in the testicles and also affect fertility.

Untreated syphilis can progress through stages and eventually cause serious damage to the brain, heart, and nervous system. This only happens if it goes untreated for years, but it's a reminder of why testing matters.

Certain strains of HPV can cause cancer, most commonly cervical cancer but also cancers of the throat, anus, and penis. The HPV vaccine, which is offered in UK schools, protects against the most dangerous strains.

Untreated HIV leads to AIDS, which destroys the immune system and can be fatal. But with modern treatment, people with HIV can keep the virus under control and live long, healthy lives.

The common thread is "untreated." Almost all of these worst-case outcomes are preventable with testing and treatment.

The worst effects of STIs come from infections that are not treated. Most STIs are easy to deal with if caught early. The problems happen when people do not get tested.

Untreated chlamydia or gonorrhoea can damage the insides of the body and make it harder to have babies later.

Untreated syphilis can damage the brain and heart over time.

Some types of HPV can cause cancer. The HPV vaccine given in schools protects against the most dangerous types.

Untreated HIV can lead to AIDS, which is very serious. But with modern medicine, people with HIV take daily tablets and live long, healthy lives.

The key word is untreated. Testing and treatment prevent almost all of these worst outcomes.