Doxycycline Explained: Uses, Side Effects & Online Prescriptions

By: Doron Nadler BPharm, MPS  ·  First Published 11 August 2026

Doxycycline is one of the antibiotics Australian doctors reach for most often. It sits in the tetracycline group and is prescribed for a broad mix of bacterial infections — from sexually transmitted infections (STIs) such as chlamydia, through to inflammatory acne, some chest infections, and a handful of tick-borne illnesses.

If you have already been prescribed doxycycline, or you are trying to work out whether it might be suitable for what you are dealing with, this guide walks through how it works, what it treats, the side effects to watch for, and how a prescription can be arranged through telehealth.

What is doxycycline?

Doxycycline is a broad-spectrum antibiotic. Rather than destroying bacteria on contact, it interferes with the machinery bacteria use to build the proteins they need to grow and divide. With reproduction stalled, your immune system is given the upper hand to clear the infection.

Because that mechanism works against so many different organisms, doxycycline has ended up being one of the more flexible antibiotics in everyday general practice.

What is doxycycline used for?

Doctors commonly prescribe doxycycline for conditions including:

• Chlamydia
• Acne vulgaris
• Rosacea
• Pelvic inflammatory disease (PID)
• Mycoplasma genitalium (alongside other antibiotics)
• Community-acquired pneumonia
• Atypical respiratory infections
• Lyme disease (where relevant)
• Tick-borne infections
• Q fever
• Some skin and soft-tissue infections
• Anti-malaria (prevention) for travellers heading to certain regions

Whether doxycycline is the right choice depends on your symptoms, your medical history, and the bacteria most likely behind the infection — a judgement your doctor makes at the point of assessment.

Doxycycline for chlamydia

Chlamydia is one of the most frequent reasons doxycycline is prescribed, and it remains among the most commonly diagnosed STIs in Australia.

Many people who have chlamydia do not have any symptoms, which is exactly why it spreads so easily — you can pass it on without ever realising you have it. When symptoms do show up, they can include:

• A burning or stinging feeling when passing urine
• Unusual discharge from the genitals
• Lower abdominal or pelvic pain
• Discomfort during sex
• Pain or swelling in the testicles
• Rectal pain or discharge

Current Australian STI guidelines place doxycycline as the first-line treatment for uncomplicated genital and throat (pharyngeal) chlamydia in most non-pregnant adults.

If you are treated for chlamydia, it helps to:

• Finish the full course of antibiotics, even once you feel fine
• Hold off on sex until your doctor gives the all-clear
• Make sure recent partners are tested and treated too
• Consider a repeat test around three months later, since reinfection is common

If you would like to arrange testing first, you can request a pathology referral for STI screening online.

Doxycycline as post-exposure prophylaxis (Doxy PEP)

Beyond treating an active infection, doxycycline is now also used by some higher-risk individuals as Doxy-PEP — doxycycline post-exposure prophylaxis. This involves taking a single oral dose of doxycycline, within 72 hours (3 days) after sex (oral, anal, or vaginal) to help prevent syphilis and chlamydia, though it works best if taken in the first 24 hours. However, it has no effect on viral infections like HIV or herpes.

Due to antibiotic resistance it is unlikely to be effective against gonorrhoea, so it is important to regularly test for STIs.

Doxy-PEP isn't right for everyone and requires a prescription to begin. During an online consultation, a MediLeave doctor can assess whether it's suitable for you based on your individual risk factors.

Doxycycline for acne

Doxycycline is also a well-established option for moderate to severe inflammatory acne.

Here it is not really working as a straightforward infection treatment. Instead, it helps by:

• Lowering the numbers of acne-driving bacteria
• Calming inflammation
• Easing redness and swelling
• Heading off new inflamed spots before they form

It is frequently paired with topical treatments such as benzoyl peroxide, retinoids, or azelaic acid. Courses usually run from several weeks to a few months and should be reviewed regularly so the antibiotic is not continued longer than it needs to be.

Doxycycline uses: other conditions doxycycline treats

Outside of STIs and acne, doxycycline turns up in the management of a range of other bacterial infections.

Respiratory infections

It is sometimes used for atypical pneumonia, certain bacterial sinus infections, chest infections, and selected cases of bronchitis. It is worth remembering that plenty of respiratory infections are viral and gain nothing from antibiotics.

Skin infections

Doxycycline may be chosen for some bacterial skin infections, including infected wounds, cellulitis caused by susceptible bacteria, rosacea, and some animal bites.

Tick-borne illnesses

It is a mainstay for several tick-transmitted infections, such as Lyme disease (where present), Queensland tick typhus, scrub typhus, and other rickettsial infections. Starting treatment early makes a real difference to how things turn out.

Doxycycline for malaria

Travellers heading into malaria-risk areas are sometimes prescribed doxycycline as a preventive. It is typically begun before departure, taken throughout the trip, and continued for a few weeks after leaving the malaria zone. Planning a trip? You can organise this through a travel health consultation.

How to take doxycycline

To keep side effects to a minimum:

• Swallow it with a full glass of water
• Stay upright for at least 30 minutes afterwards
• Avoid taking it right before lying down for the night
• Follow your doctor's advice about taking it with or without food
• Finish the whole course, even once symptoms settle

Taking doxycycline the wrong way can irritate — and in some cases ulcerate — the oesophagus (the tube that carries food to your stomach), which is why staying upright and drinking plenty of water matters.

Doxycycline side effects

As with any antibiotic, doxycycline can cause side effects. The more common ones include:

• Nausea
• An unsettled stomach
• Diarrhoea
• Heightened sensitivity to sunlight
• Headache
• Vaginal thrush

The sun sensitivity is worth taking seriously — sunscreen, covering up, and steering clear of long stretches in strong sun all help reduce the chance of a nasty burn.

Who should not take doxycycline?

Doxycycline is not the right fit for everyone. Let your doctor know if you:

• Are pregnant or trying to conceive
• Are breastfeeding
• Have liver problems
• Have trouble swallowing
• Have previously reacted to a tetracycline antibiotic
• Take other medicines that could interact with it

Where doxycycline is not suitable, your doctor can weigh up an alternative antibiotic instead.

Doxycycline and alcohol

A modest amount of alcohol generally will not stop doxycycline from doing its job. Heavy or ongoing drinking is a different story — it can blunt how well the antibiotic works and add to the risk of dehydration and stomach upset.

Can I get doxycycline online?

Yes. Where it is clinically appropriate, an Australian-registered doctor can assess your situation through telehealth and prescribe doxycycline if it is the right call.

Not every situation suits a telehealth assessment, and antibiotics are only ever prescribed when there is a clear clinical reason after a proper medical review.

Doxycycline and antibiotic resistance

Antibiotic resistance is one of the bigger public-health challenges we face globally. You can help protect these medicines by:

• Only taking antibiotics when they have been prescribed for you
• Never sharing them with anyone else
• Completing the full course
• Not dipping into leftover antibiotics from a previous illness
• Going back for review if symptoms are not clearing

Using antibiotics thoughtfully now is what keeps them working for the people who will need them later.