Learn about sexually transmitted infections
Clear, evidence-based guides to the most common STIs — symptoms, transmission, testing windows, and treatment options. Written for real people, reviewed by specialists.
Major infections
HIV
Human Immunodeficiency Virus
A virus that attacks the immune system. With modern treatment, people with HIV live long, healthy lives. Early diagnosis and PEP after exposure are critical.
Testing window
45 days (4th gen)
Treatable
Yes — antiretrovirals
Common route
Unprotected sex, blood
Chlamydia
Chlamydia trachomatis
The most commonly diagnosed STI. Often has no symptoms, especially in women. Easily treated with a short course of antibiotics.
Testing window
2 weeks
Treatable
Yes — antibiotics
Symptoms
Often none (70%)
Gonorrhoea
Neisseria gonorrhoeae
A bacterial infection that can affect the genitals, rectum, and throat. Rates are rising. Antibiotic resistance is a growing concern.
Testing window
2 weeks
Treatable
Yes — dual antibiotics
Resistance
Increasing concern
Syphilis
Treponema pallidum
A bacterial infection with four distinct stages. Early stages are highly treatable. Later stages can cause serious health complications if left untreated.
Testing window
6 weeks
Treatable
Yes — penicillin
Stages
4 (primary to latent)
Herpes
Herpes Simplex Virus (HSV-1 & HSV-2)
A very common viral infection causing recurrent outbreaks. There is no cure, but antiviral medication can manage outbreaks and reduce transmission risk significantly.
Testing window
12+ weeks (blood test)
Curable
No — manageable
Prevalence
~67% have HSV-1
HPV
Human Papillomavirus
The most common sexually transmitted infection. Most infections clear on their own. Some strains cause genital warts; others are linked to certain cancers.
Vaccine available
Yes — highly effective
Curable
No test for adults
Prevalence
Extremely common
Other infections
Less commonly discussed, but important to understand.