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.
Doxycycline is the workhorse antibiotic of sexual health care. It’s the first-line treatment for chlamydia, non-specific urethritis, LGV and part of the treatment for mycoplasma genitalium. It’s also being used as DoxyPEP (post-exposure prophylaxis for bacterial STIs) in some settings. Doxycycline is effective, well tolerated and affordable.
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Uses in Sexual Health
| Condition | Dose |
|---|---|
| Chlamydia | 100mg twice daily for 7 days |
| Non-specific urethritis | 100mg twice daily for 7 days |
| LGV | 100mg twice daily for 21 days |
| Mycoplasma genitalium | 100mg twice daily for 7 days (before azithromycin/moxifloxacin) |
| DoxyPEP | 200mg within 72 hours after sex |
| Syphilis (penicillin allergy) | 100mg twice daily for 14-28 days |
How to Take It
- Take with plenty of water
- Don’t lie down for 30 minutes after (reduces oesophageal irritation)
- Take with food to reduce nausea
- Avoid antacids, iron and calcium within 2 hours
- Use sun protection — photosensitivity is common
Side Effects
- Nausea
- Photosensitivity (sunburn risk)
- Oesophageal irritation
- Thrush (from antibiotic effect on normal bacteria)
Who Should Avoid It
- Pregnant women (use azithromycin instead)
- Children under 12
- People with severe liver disease
Read more: Azithromycin | Best antibiotics for STIs | DoxyPEP
Frequently Asked Questions
Why is doxycycline preferred over azithromycin for chlamydia?
Higher cure rates and less risk of driving antibiotic resistance.
Can I drink alcohol on doxycycline?
Moderate alcohol is usually fine — unlike metronidazole.
Does doxycycline cause sun sensitivity?
Yes — use sunscreen and avoid prolonged sun exposure.
Related reading
- Using Antibiotics to Prevent STIs: DoxyPEP Explained
- Azithromycin: Uses in Sexual Health
- Best Antibiotics for STIs: A Practical Guide
- Ciprofloxacin for STIs: Uses, Dosage, and Side Effects
- Clindamycin: Uses in Sexual Health
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.
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