References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
Pelvic inflammatory disease (PID) is an infection of the upper female reproductive tract — the uterus, fallopian tubes and ovaries. It’s usually caused by bacteria from untreated STIs, most commonly chlamydia and gonorrhoea. PID can cause chronic pelvic pain, infertility and ectopic pregnancy if not treated promptly. Early antibiotic treatment prevents most complications.
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Symptoms
- Lower abdominal or pelvic pain
- Unusual vaginal discharge
- Bleeding between periods or after sex
- Pain during sex
- Fever
- Pain on urination
- Sometimes no symptoms at all
Causes
| Cause | How Common |
|---|---|
| Chlamydia | Most common |
| Gonorrhoea | Common |
| Mycoplasma genitalium | Increasingly recognised |
| Normal vaginal bacteria | Sometimes |
| After procedures (IUD insertion) | Rare |
Complications
- Infertility from tubal scarring
- Ectopic pregnancy
- Chronic pelvic pain
- Tubo-ovarian abscess (serious)
Treatment
- Antibiotics covering chlamydia, gonorrhoea and anaerobes
- Usually a 14-day course
- Partners tested and treated
- Hospital admission if severe
Prevention
- Regular STI testing
- Prompt treatment of chlamydia and gonorrhoea
- Condoms
- Partner treatment
Read more: STIs and infertility | What is chlamydia? | STI symptoms in women
Frequently Asked Questions
Can PID be cured?
Yes with antibiotics, but existing damage may not reverse.
Can PID happen without an STI?
Sometimes — normal vaginal bacteria can cause it rarely.
Does PID always cause infertility?
No — prompt treatment prevents most fertility problems.
Related reading
- What Is a Female (Internal) Condom?
- What Is a Shigella Infection?
- What Is Bacterial Vaginosis (BV)?
- What Is Gonococcal Arthritis?
- What Is Human Papillomavirus (HPV)?
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
