Doxycycline — NZ Medication Guide
📋 Reviewed by a Registered Pharmacist NZ — This information is for general educational purposes only and does not replace professional medical advice. Always consult your doctor or pharmacist before starting, stopping, or changing any medication.
What is Doxycycline?
Doxycycline is a broad-spectrum tetracycline antibiotic used for a wide range of bacterial infections and as malaria prophylaxis. This medication is funded by Pharmac for various bacterial infections and malaria prophylaxis.
What is Doxycycline Used For?
Doxycycline is used for respiratory tract infections (community-acquired pneumonia, atypical pneumonias including Mycoplasma and Chlamydia), sexually transmitted infections (chlamydia, pelvic inflammatory disease, syphilis), skin and soft tissue infections, Lyme disease, malaria prophylaxis, rosacea, and periodontal disease.
How Does Doxycycline Work?
Doxycycline inhibits bacterial protein synthesis by reversibly binding to the 30S ribosomal subunit, blocking the binding of aminoacyl-tRNA to the mRNA-ribosome complex. This inhibits elongation of the polypeptide chain — bacteriostatic effect at therapeutic concentrations.
How to Take Doxycycline
Taken once daily (100 mg) or twice daily (50–100 mg) depending on the infection. Take with a full glass of water — remain upright for at least 30 minutes after taking to prevent oesophageal irritation. Take with food if nausea is a problem (slight reduction in absorption is acceptable). Do not take within 2 hours of dairy products, antacids, or iron.
Common Side Effects of Doxycycline
- Nausea and oesophageal irritation (take with plenty of water and remain upright)
- Photosensitivity (sunburn more easily — use sunscreen and avoid prolonged sun exposure)
- Headache
- Diarrhoea
- Vaginal candidiasis (thrush in women)
Serious Side Effects — Seek Medical Attention
Contact your doctor or call 111 immediately if you experience any of the following:
- Oesophageal ulceration (if not taken with adequate water or lying down)
- Severe photosensitivity reactions
- Intracranial hypertension (pseudotumor cerebri — rare — headache and visual changes)
- Severe skin reactions (Stevens-Johnson syndrome — rare)
- Clostridioides difficile colitis
Drug Interactions
Doxycycline may interact with other medicines. Always inform your doctor and pharmacist of all medications you are taking. Key interactions include:
- Antacids, calcium, iron, magnesium, dairy products (chelate doxycycline — drastically reduce absorption — take 2–3 hours apart)
- Warfarin (enhanced anticoagulant effect)
- Retinoids (additive intracranial hypertension risk — avoid combination)
- Barbiturates, carbamazepine, phenytoin (reduce doxycycline half-life)
New Zealand Prescribing Information
Doxycycline (50 mg, 100 mg capsules and tablets) is funded by Pharmac. It is the most widely used tetracycline in NZ. Doxycycline is contraindicated in pregnancy (permanent staining of fetal teeth) and in children under 8 years. Malaria prophylaxis dose: 100 mg daily, starting 1–2 days before travel to a malaria-endemic area and continuing for 4 weeks after return.
Frequently Asked Questions
Can I take doxycycline with food or milk?
Dairy products (milk, cheese, yoghurt), antacids, and iron supplements significantly reduce doxycycline absorption by chelation. Take doxycycline with a full glass of plain water, avoiding these foods for 2 hours before and after your dose. Taking it with a small non-dairy snack reduces nausea without significantly affecting absorption.
Does doxycycline make me more sensitive to sunlight?
Yes — doxycycline causes photosensitivity, making your skin more susceptible to sunburn. Apply SPF 50+ broad-spectrum sunscreen daily, wear protective clothing, and avoid prolonged sun exposure while taking this medicine.
⚠️ Disclaimer: This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or a qualified health provider. In New Zealand, medication availability and funding may vary — check with Pharmac or your pharmacist for current information.
Reviewed by a Registered Pharmacist NZ
References & Further Information
The following New Zealand and international resources were used to inform this page: