Doxy-PEP (doxycycline post-exposure prophylaxis): Should I take antibiotics to prevent STIs?

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Decision-aid for consumers

What is this decision aid for?

This decision-aid can help you decide whether to use antibiotics after sex to reduce your risk of contracting syphilis and chlamydia. Consider taking this resource to your doctor’s appointment to help make a shared and informed decision about whether Doxy-PEP is right for you.

What is Doxy-PEP?

Doxy-PEP means taking an oral dose of an antibiotic called doxycycline within 72 hours (3 days) of having sex (oral, anal, or vaginal) to protect against syphilis and chlamydia. Doxycycline is a safe and common medication used to treat certain infections, control acne, and prevent malaria. It does not work against viral infections such as HIV or herpes.

Who can benefit most from Doxy-PEP?

Doxy-PEP is most likely to benefit people at higher risk of syphilis, such as gay, bisexual, and other men who have sex with men, and transgender women, especially with recent syphilis or multiple recent sexually transmissible infections (STIs). It may also benefit others who want to reduce their risk of STIs including people taking HIV pre-exposure prophylaxis (PrEP), and commercial sex workers after a condom break.

Doxy-PEP reduces the risk of syphilis (by 70-80%) and chlamydia (by 70-90%). Due to antibiotic resistance it is unlikely to be effective against gonorrhoea, so it is important to regularly test for STIs.

Potential benefits

  • Prevent syphilis and chlamydia infection.
  • Reduce the spread of STIs within your sexual networks.
  • Provide added protection alongside condoms and STI testing.

Potential risks*

  • Common but non-serious side effects including nausea, vomiting and diarrhoea.
  • Your skin may become more sensitive to sunlight, causing a rash or sunburn.
  • Rare but serious reactions like allergies, oesophageal ulcers or liver damage.
  • If used after 18 weeks of pregnancy, can cause bone and teeth defects in your baby.
  • May contribute to antibiotic resistance in your body, or in the community, and reduce your future treatment options for STIs and other infections. This may be important for people with weakened immune systems or chronic diseases, as they are more likely to have frequent or severe bacterial infections.

*For more safety information see Safety information about doxycycline.

Making an informed decision

Doxy-PEP is one approach among several for preventing STIs. An open conversation with your doctor can help determine if Doxy-PEP is suitable for you based on your specific needs.

Discuss with your doctor:

  • your personal STI risk factors
  • the benefits and potential risks of Doxy-PEP for your situation
  • dosing instructions and what to expect if Doxy-PEP is recommended
  • taking HIV pre-exposure prophylaxis (PrEP) if you are at risk of HIV.

If you have any concerns about taking doxycycline or experience any adverse effects from this medicine, speak with your doctor or pharmacist. If you decide to take Doxy-PEP, it is recommended to visit your doctor after 3 to 6 months to assess if you need to keep using it.

About antibiotic resistance (antimicrobial resistance)

Using antibiotics causes bacteria to develop resistance, making them less effective for treating infections. Antibiotic resistance is a problem throughout the world and is a major threat to human health. For STIs, this is an issue for gonorrhoea. Widespread use of Doxy-PEP may increase resistant gonorrhoea strains in the community. It is important to weigh these concerns against the benefits of Doxy-PEP, particularly in preventing the serious health complications associated with syphilis .

Using Doxy-PEP

How do I take Doxy-PEP?

  • Take two 100 mg doxycycline tablets or capsules once within 72-hours (3 days) after having sex (oral, anal, or vaginal sex).
  • Take doxycycline with food and a full glass of water to prevent stomach upset. Do not lie down for at least an hour after swallowing the tablets, to avoid irritation of your food pipe.
  • Do not take Doxy-PEP more than once every 3 days.
  • Do not take antacids, iron, calcium. zinc or fibre supplements within 2 hours of doxycycline as they may interfere with its absorption.
  • Apply sunscreen when out in the sun to avoid sunburn.

Safety information about doxycycline

  • Do not take doxycycline if you have a known tetracycline allergy - the class of antibiotics to which doxycycline belongs.
  • Do not take doxycycline after the 18th week of pregnancy.
  • Discuss the risks and benefits of taking doxycycline while breastfeeding with your doctor. Short courses (7-10 days) are considered safe. Expert advice can be sought from MotherSafe at (02) 9382 6539 (Sydney metropolitan area) or 1800 647 848 (non-metropolitan area).
  • Consult your doctor or pharmacist about possible interactions if you are taking any of the following:
    • vitamin A preparations and medicines for skin problems (e.g., isotretinoin, etretinate)
    • Warfarin, a medicine used to prevent blood clotting
    • penicillins, another group of antibiotics (e.g., amoxicillin)
    • epilepsy medicines (e.g., phenytoin, carbamazepine, phenobarbitone)
    • birth control pills, as doxycycline may decrease their effectiveness, requiring additional contraception.

Other ways to prevent STIs

  • Get tested regularly and treat any STIs promptly
  • Use condoms consistently and correctly

Where can I get more information?

  • Sexual Health Infolink (SHIL), a confidential telephone help line: 1800 451 624 between 9:00am and 5:30pm Monday to Friday
  • Visit SHIL - Prevention for more information on STI prevention.

Prescriber information

Doxy-PEP is primarily recommended for people at increased risk of syphilis but can be prescribed to anyone (without a specific contraindication) who wishes to reduce their risk of syphilis and chlamydia and understands the risks and benefits. The need for ongoing Doxy-PEP should be reviewed at least every 6-months.

Prescribe doxycycline 200mg orally as a single dose up to 72 hours after sex.

Most people should be provided with a private prescription for 28 tablets with sufficient repeats to last up to 6-months. For concession card holders and those eligible under the Closing The Gap – PBS Co-payment program, it may be more cost effective to provide a PBS prescription. Under the PBS General Schedule, this is limited to 7 tablets with 1 repeat. Contact Services Australia (132 290) for clarification about PBS listings or the prescribing process.

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Current as at: Thursday 26 September 2024
Contact page owner: Centre for Population Health