Breastfeeding Week: Are Your Medicines Safe?

Here's a statistic that stops most new parents mid-scroll: around 96% of Australian mothers start out breastfeeding their baby — one of the highest initiation rates in the world — yet by six months, only about a third are still exclusively breastfeeding, according to the Australian Breastfeeding Association. That's a huge gap between what Australian families want to do and what actually happens.

And one of the quiet, under-discussed reasons behind that gap? Medicines.

Somewhere in Australia right now, a mum with a splitting sinus headache is staring at a box of cold and flu tablets wondering if one dose will "contaminate" her milk. Another has a script for antibiotics sitting on the kitchen bench, untouched, because the pharmacy label said "consult your doctor if breastfeeding." Someone else has been told by a well-meaning relative to "pump and dump for 24 hours" after taking a single paracetamol. Meanwhile, a mother with postnatal depression is quietly not filling her antidepressant script because she believes she has to choose between her mental health and her baby's milk.

Here's the reassuring truth, and it comes straight from the Australian Breastfeeding Association: most medicines are safe to take while breastfeeding. All medications enter breastmilk, but usually only in tiny amounts — and "tiny" is doing a lot of important work in that sentence.

This World Breastfeeding Week — marked every year from 1 to 7 August and coordinated globally by the World Alliance for Breastfeeding Action — we want to tackle the topic that generates more anxious 2am Google searches than almost any other: medicines while breastfeeding.

In this guide, we'll explain how medicines actually pass into breastmilk (it's more reassuring than you think), walk through the most common medicine categories Australian parents ask us about — pain relief, cold and flu products, antibiotics, mental health medicines, contraception and herbal supplements — flag the small handful of drugs that genuinely aren't compatible with breastfeeding, list the free Australian services you can call for expert advice, and show you how our Australian-registered doctors can complete a prescription review online without you having to bundle a newborn into the car.

Because "when in doubt, stop breastfeeding" is almost never the right answer. Let's talk about what is.

Why Breastfeeding Medication Safety Gets So Confusing

If you've ever read a medicine's consumer information leaflet while breastfeeding, you've probably noticed the language is cautious to the point of unhelpful. Phrases like "should not be used unless clearly necessary" or "consult your doctor" appear constantly.

There's a structural reason for that. Pregnant and breastfeeding women are, understandably, rarely included in clinical drug trials. So when a medicine is approved, the manufacturer often has limited trial data in lactating women — and the legally safest position is a blanket caution. That caution then gets printed on the box, read by a sleep-deprived parent at 3am, and interpreted as "this will harm my baby."

But absence of trial data isn't the same as evidence of harm. Over decades, researchers have built a substantial body of real-world evidence on drugs in lactation — measuring how much of a medicine actually appears in milk, how much a baby absorbs, and what happens to infants exposed through breastfeeding. That's why specialist services and reference databases exist, and why they can often say "yes, this is fine" when a packet insert says "ask your doctor."

The consequence of the confusion, though, is real. Parents stop taking medicines they need. Or they stop breastfeeding when they didn't need to. Both outcomes are avoidable.

How Medicines Actually Get Into Breastmilk

You don't need a pharmacology degree, but understanding the basic mechanics makes the advice click into place.

When you take a medicine, it's absorbed into your bloodstream. Your milk-making cells sit alongside those blood vessels, so a small fraction of the drug can diffuse across into milk. Several factors determine how much:

Molecular size. Large molecules struggle to cross into milk at all. This is why injected biologic medicines, insulin and heparin are generally considered compatible with breastfeeding — the molecules are simply too big, and many are also destroyed by the baby's digestive system.

Protein binding. Many drugs travel through blood attached to proteins. Only the unbound portion can slip into milk, so heavily protein-bound medicines transfer poorly.

Half-life. Medicines that clear your system quickly spend less time available to enter milk. Long-acting drugs, or drugs with long-acting active metabolites, need more thought — especially in the newborn period.

Oral availability in the baby. Even if a drug reaches milk, the infant's gut has to absorb it. Plenty of medicines are broken down before they do anything.

Clinicians pull these factors together into a concept called the relative infant dose — roughly, the dose the baby receives via milk compared with the mother's dose, adjusted for weight. As a rule of thumb, when that figure is very low, the exposure is considered negligible. For a detailed clinical overview written for Australian prescribers, Australian Prescriber's article on drugs in breastfeeding is an excellent (and freely available) read.

One practical tip from that same source: where possible, feed your baby first, then take your medicine, so the drug concentration in milk is at its lowest during feeds. And reassuringly, drugs don't "store" in your milk waiting to ambush the next feed — as your blood levels fall, the medicine moves back out of the milk into your bloodstream. (The main exception is medicines with a very long half-life, which is exactly the situation where individual advice matters.)

The Medicines Australian Parents Ask Us About Most

Below is a plain-English tour of the categories that come up again and again. This is general information, not a substitute for advice about your medicine, your dose and your baby — but it should help you ask better questions.

Pain relief and fever

Paracetamol and ibuprofen are the standard go-to options and are widely considered compatible with breastfeeding when taken at recommended doses. Ibuprofen in particular transfers into milk in extremely small amounts.

Codeine is a different story. Following a safety review, Australia's Therapeutic Goods Administration advises that codeine should not be used by breastfeeding mothers, or by people known to be ultra-rapid metabolisers. The reason is genetics: some people convert codeine to morphine unusually quickly, which can lead to dangerously high morphine levels in milk. This was also part of why all codeine-containing products in Australia moved to prescription-only from February 2018. If you were prescribed codeine before you were breastfeeding, or you have leftovers in the cupboard from a previous injury, this is a conversation to have with a doctor rather than a decision to make yourself.

Cold, flu and hay fever products

This is the category with the most surprising twist. Pharmacy cold-and-flu products often contain pseudoephedrine, a decongestant. The infant safety concern is minimal — but the effect on you may not be. A landmark Western Australian study published in the British Journal of Clinical Pharmacology found that a single 60 mg dose of pseudoephedrine reduced milk production measurably over 24 hours, likely via an effect on prolactin.

So if you're breastfeeding — and especially if your supply is already borderline — reaching for a multi-symptom cold tablet may cost you more than it gives you. Saline sprays, steam inhalation, rest and fluids are unglamorous but supply-friendly. Topical nasal sprays work locally and don't have the same whole-body effect.

For hay fever, healthdirect advises that non-drowsy antihistamines are considered safe while breastfeeding, and that nasal sprays and eye drops are safe too. Sedating antihistamines aren't recommended, because they may make your baby sleepy as well as you.

Antibiotics — including for mastitis

Most commonly prescribed antibiotics are compatible with breastfeeding. This matters enormously for mastitis, where the modern advice is clear: keep breastfeeding or expressing from the affected breast. Stopping suddenly tends to make engorgement, blocked ducts and inflammation worse, not better.

Some antibiotics may cause loose stools or nappy rash in a breastfed baby, or occasionally oral thrush, but these are usually mild and temporary. If you develop a red, hot, painful wedge of breast tissue plus fever and flu-like aching, don't wait it out — mastitis can escalate quickly, and early treatment protects both your supply and your wellbeing. A telehealth consultation can often get you assessed and treated the same day.

Mental health medicines

Perinatal mental health deserves far more than a paragraph, but here's the headline: Australian Prescriber notes that SSRIs are generally safe to use during lactation, with sertraline commonly favoured because of its pharmacological profile. Highly sedating antidepressants are generally avoided, partly because a drowsy parent caring for a newborn creates its own risks.

There's also a two-way relationship worth knowing about: women who develop postnatal depression are more likely to stop breastfeeding, while women who establish and maintain breastfeeding are less likely to develop depression. Treating a parent's mental health is not in competition with breastfeeding — it often supports it.

If you have been quietly skipping doses because you're scared, please make that the thing you talk to a doctor about this week. You deserve treatment, and your baby needs a well parent.

Contraception and sexual health after birth

Fertility can return sooner than people expect, and breastfeeding is not reliable contraception on its own. The good news is that plenty of options are breastfeeding-friendly. The Better Health Channel explains that the progestogen-only pill can be started straight after birth, even while breastfeeding, and healthdirect notes the same for the mini-pill. Hormonal and copper IUDs are also considered safe during breastfeeding.

Oestrogen-containing combined pills are the ones that warrant a conversation, because oestrogen can affect supply — particularly in the early weeks while lactation is still being established. Timing matters, so it's worth an individualised discussion rather than a guess.

While we're here: pain during sex, vaginal dryness (very common with the hormonal shifts of lactation), low libido and pelvic floor concerns are all legitimate medical topics, not things to endure silently. Same goes for STI testing and treatment — most treatments are breastfeeding-compatible, and delaying care helps nobody.

Herbal, "natural" and complementary products

This is where instincts often mislead people. "Natural" does not automatically mean "safer while breastfeeding." As the Australian Breastfeeding Association points out, herbal products don't have to go through the same safety checks as prescription medicines, which means we often know less about their effects during lactation, not more. healthdirect similarly notes that for most herbal and traditional medicines there isn't enough research to confirm safety while breastfeeding.

Lactation "boosting" teas, high-dose supplements, weight-loss products and imported remedies all fall into this bucket. Tell your pharmacist or doctor about everything you're taking — including things bought online or brought from overseas — not just the items on a prescription.

The genuinely incompatible list

It's short, and that's the point. Australian Prescriber lists drugs contraindicated during breastfeeding as including anticancer drugs, lithium, oral retinoids, amiodarone and gold salts. Certain diagnostic procedures using radioactive substances also require a temporary interruption to breastfeeding.

If you're prescribed something in this category, that's not automatically the end of your breastfeeding journey. It's the beginning of a plan: how long to interrupt, how to maintain supply by expressing, whether stored milk or formula bridges the gap, and how to re-establish feeding afterwards. Australian Breastfeeding Association counsellors are genuinely excellent at helping families build that plan.

Free Australian Services You Can Call Today

One of the best things about navigating breastfeeding medication safety in Australia is that expert help is free and close at hand. Save these in your phone:

• MotherSafe (Royal Hospital for Women, Randwick) — free counselling about exposures during pregnancy and breastfeeding, including prescription and over-the-counter medicines. Call (02) 9382 6539 in Sydney metro or 1800 647 848 for NSW non-metro. Available to callers and clinicians alike.
• Australian Breastfeeding Association National Breastfeeding Helpline — 1800 686 268, staffed by trained breastfeeding counsellors.
• healthdirect — 1800 022 222 (NURSE-ON-CALL in Victoria), a registered nurse 24/7.
• Pregnancy, Birth and Baby — 1800 882 436 to speak with a maternal child health nurse, or use their medicines and breastfeeding page.
• Medicines Information Service, Women's and Children's Hospital (SA) — (08) 8161 7555.
• Your local pharmacist — genuinely underrated. They can check compatibility on the spot.
• LactMed — a free, peer-reviewed database on drugs and lactation, written for health professionals but usable by anyone comfortable with clinical language.

Queensland Health also publishes a helpful consumer factsheet on breastfeeding and medicines if you'd like something to print and stick on the fridge.

Signs to Watch For in Your Baby

If you're taking any medicine while breastfeeding, keep a casual eye out for changes in your baby and mention them promptly:

• Unusual sleepiness or difficulty waking for feeds
• Poor sucking, refusing feeds, or reduced wet nappies
• Unusual irritability or high-pitched crying
• Loose stools, vomiting or new rash
• Any change in breathing, colour or floppiness — this is a call-000 situation, immediately

Most of the time, nothing happens. But you know your baby's normal better than anyone, and "something's different since I started this medicine" is always worth a phone call.

Five Myths Worth Deleting From Your Brain

"All medicines pass into milk, so all medicines are dangerous." All medicines do pass into milk. Almost all of them do so in amounts too small to matter.

"Pump and dump just to be safe." Expressing and discarding milk doesn't speed up drug clearance from your body — milk levels fall as your blood levels fall. Expressing is useful for comfort and supply during a genuine interruption, not as a routine detox ritual.

"Stopping breastfeeding is the cautious choice." Weaning has real costs for your baby's health, your own health, and your budget. The cautious choice is getting accurate information.

"The pharmacist said ask my doctor, so it must be risky." That phrase is often a legal default, not a clinical verdict.

"I should just wait until my next GP appointment in three weeks." Untreated infections, unmanaged pain and untreated depression all get harder, not easier, with time.

How We Can Help — Without You Leaving the House

Anyone who has tried to attend an appointment with a newborn, a nappy bag and a feeding schedule knows the logistics are brutal. That's exactly the problem we built NextClinic to solve.

We're an Australian telehealth service, and our registered practitioners can help with:

• Prescription review online. If you've been prescribed a medicine and you're breastfeeding, we can review it, discuss the evidence, and where appropriate suggest a more lactation-friendly alternative or adjust the plan — all without a waiting room.
• Repeat prescriptions. Chronic conditions don't pause for parenthood. Asthma, thyroid conditions, reflux, epilepsy, contraception, mental health medicines — we can assess and issue scripts where clinically appropriate.
• Medical certificates for sick leave and carer's leave. If mastitis has flattened you, or you need to care for an unwell baby, we can issue an online medical certificate after a consultation so you can rest without an argument with HR.
• Specialist referrals. Whether it's a lactation consultant, an obstetrician, a perinatal psychiatrist, a dermatologist or an endocrinologist, we can arrange the referral you need.
• Telehealth consultations for the everyday things — infections, skin issues, sexual health concerns, mental health check-ins.

We'll also be honest about our limits. Telehealth isn't the right tool for a baby who is unwell, for suspected breast abscess, for severe pain, or for any emergency. In those situations we'll tell you plainly to see someone in person, and if it's urgent, call 000. You can browse more of our practical guides over on our blog.

Your Breastfeeding Week Challenge

Let's bring it home. The most important things to carry away from this post:

Most medicines are compatible with breastfeeding. All drugs enter milk, but usually in tiny amounts, and the genuinely contraindicated list is short.

Cautious packet warnings reflect missing trial data, not proven harm. Real-world evidence often tells a much more reassuring story.

Watch out for the sneaky supply-related risks, especially pseudoephedrine-containing cold and flu products and oestrogen-containing contraceptives, rather than assuming every medicine is an infant-safety issue.

Codeine is a genuine no while breastfeeding, per the TGA — and "natural" or herbal products aren't automatically safer just because they're not prescription.

Treating your own health is part of caring for your baby, and that includes postnatal depression and anxiety.

Australia has free, expert, evidence-based advice a phone call away. MotherSafe, the ABA helpline, healthdirect, Pregnancy Birth and Baby, and your local pharmacist.

Now, here's your challenge for this week. Pick one action and actually do it before World Breastfeeding Week wraps up:

1. Open your medicine cupboard, take a photo of everything you're currently taking — prescription, over-the-counter, vitamins, herbal — and get it checked in one go.
2. Save 1800 647 848 (MotherSafe) and 1800 686 268 (ABA Helpline) into your phone right now.
3. Book a prescription review online with us to sort out that one medicine you've been quietly worrying about.
4. If you've been avoiding a mental health conversation, have it this week.
5. Replace your cold-and-flu multi-symptom tablets with a saline nasal spray, so the decision is already made next time you're unwell at 2am.

Then tell us in the comments: which one did you pick, and what did you find out? If a pharmacist or a helpline gave you an answer that surprised you — or a piece of advice that finally let you stop worrying — share it. Someone else scrolling this page at 3am with a baby on the boob and a box of tablets in their hand will be very glad you did.

This article is general information for Australian residents and isn't a substitute for personalised medical advice. Always discuss your specific medicines, doses and circumstances with a qualified health professional. In an emergency, call 000.

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