Worried you may have an STI?
Evidence-based information to help you understand your symptoms, assess your risk and decide what to do next. Clear, honest and completely private.
Check Symptoms
I have symptoms I'm concerned about
Assess an Exposure
Something happened — what is my risk?
Learn About STIs
Understand specific infections
Testing Timeline
When should I get tested?
This website provides educational information only. It is not a substitute for professional medical advice, diagnosis or treatment.
Get a personalised answer
Our guided tools help you work through your specific situation step by step, without judgment and completely privately.
Symptom Checker
Answer a few questions about your symptoms and get guidance on what they might mean and what to do next.
Exposure Checker
Tell us what happened and we'll help you understand your risk level and whether you need to take action.
STI Testing Timeline
Generate a full infection-by-infection Gantt chart showing when to test, when symptoms may appear, and where you stand today.
Global Infection Map
PopularSee STI prevalence and outbreak alert levels for every country. Click any country to instantly view its top five infections, alert status, and what travellers or residents should know — all in one place.
Learn about specific STIs
Clear, evidence-based guides to the most common sexually transmitted infections.
HIV
Human Immunodeficiency Virus
Transmission, prevention, testing windows, PEP and living well with HIV.
Chlamydia
Chlamydia trachomatis
The most common bacterial STI. Often symptomless but easily treated.
Gonorrhoea
Neisseria gonorrhoeae
Symptoms, testing, antibiotic resistance and what to expect from treatment.
Syphilis
Treponema pallidum
Understanding the four stages and why early diagnosis matters.
Herpes
HSV-1 and HSV-2
Outbreaks, transmission risk, suppressive therapy and living with herpes.
HPV
Human Papillomavirus
Vaccination, warts, high-risk strains and cervical screening explained.
Not seeing the infection you are looking for?
These six are among the most common — but we cover 15 infections in total, including Trichomoniasis, Hepatitis B & C, Mpox, Mycoplasma Genitalium, and more.
What brought you here today?
Select the situation that best describes what you're concerned about and get immediate, relevant guidance.
Latest articles
Reviewed by sexual health specialists. Written for real people.
What is PEP and Should You Take It?
Post-Exposure Prophylaxis can prevent HIV infection if started within 72 hours. This guide covers how PEP works, who it is for, where to get it, and what to expect.
Chlamydia: All You Need to Know
A comprehensive, science-based guide to chlamydia—covering symptoms, risks, testing, treatment, prevention, and FAQs to help sexually active individuals understand and protect their sexual health.
A Complete Guide to PrEP
Pre-Exposure Prophylaxis is one of the most effective HIV prevention tools available. Learn how it works, who should consider it, and how to access it on the NHS.
Can Chlamydia Affect Fertility?
Untreated chlamydia is a leading preventable cause of pelvic inflammatory disease and infertility. Understanding the long-term risk and why early detection matters.
Gonorrhoea and Antibiotic Resistance: What You Need to Know
Drug-resistant gonorrhoea is a growing public health concern. This article explains the current treatment landscape and what it means for you.
Hepatitis B and C: Are They Sexually Transmitted?
Hepatitis B can be sexually transmitted; hepatitis C is less commonly so but still possible in certain circumstances. What you need to know about prevention and testing.