Medications While Breastfeeding: What Is Allowed — and How to Time Doses and Feeds

A headache, a bladder infection, a cold that will not shift — and the question is there immediately: stop breastfeeding or grit your teeth? Usually both are the wrong answer. For almost every common complaint there are active substances that count as well tolerated while breastfeeding. And with the right timing, the amount that reaches your child can be kept smaller still. This guide shows which medicines are considered the standard choice, where genuine caution is called for — and which source is worth more than any package leaflet.

1. The "better stop breastfeeding" reflex — why it is usually the poorer choice

The worry is understandable: what I swallow ends up in the milk, and my child is small. So better to stop. In practice, though, that is often the decision with the greater harm — it trades a real risk for one that is usually theoretical.

Breastfeeding has documented benefits for mother and child, and a breastfeeding relationship that has been broken off often cannot be built up again. Set against that, with the great majority of common active substances the amount in the milk lies far below what would produce any effect in an infant. For everyday complaints — pain, fever, infections, allergies — there are medicines that have been used and documented in breastfeeding for decades.^¹

The second reflex is just as unhelpful: simply leaving out the tablet and "getting through it". Spending three days flat out with a migraine instead of taking a painkiller compatible with breastfeeding helps nobody.

2. embryotox.de: the reference you can rely on

If you remember only one thing from this article, make it this: embryotox.de — the pharmacovigilance and advisory centre for embryonic toxicology at the Charité, Universitätsmedizin Berlin. The database assesses active substances for pregnancy and for breastfeeding; it is public, free of charge and written in plain language. It is a German-language site.^¹

• Enter the active substance, not the brand name: the database is sorted by substance — the name is on the pack, underneath the product name.
• Look for the "Stillzeit" section: pregnancy and breastfeeding are assessed separately and the verdicts can differ.
• Take the wording seriously: "Mittel der Wahl" (agent of choice) is a clear recommendation, "akzeptabel" (acceptable) is the second option, and "nur bei zwingender Indikation" (only where there is a compelling indication) is the case for a genuine medical weighing-up. For complicated cases there is individual advice on top of that.

embryotox does not replace your doctor, but it does give you a solid basis for the conversation. Also usable alongside it: gesund.bund.de (the German national health portal) and gesundheitsinformation.de, run by the German Institute for Quality and Efficiency in Health Care (IQWiG).

3. How an active substance gets into the milk in the first place

A substance has to clear three hurdles before it can have any effect on your child.

Hurdle 1: from the blood into the milk

The milk-producing gland is not an open door. Whether a substance gets into it depends above all on three properties:

• Molecule size: large molecules do not fit through. That is why insulin, for instance, is considered unproblematic — it is too large, and it would be digested in the child's stomach anyway.
• Protein binding: many substances travel through the blood coupled to transport proteins. Whatever is bound stays in the blood — so high protein binding means little transfer.
• Fat solubility: breast milk contains fat, and strongly fat-soluble substances are more likely to accumulate in it.^²

Hurdle 2: from the child's stomach into the blood

Not everything that is in the milk is absorbed. Some substances are broken down in the child's digestive tract — they are measurable in the milk but barely reach the child's circulation at all.

Hurdle 3: the amount has to be relevant

This is where the most important figure comes in: the relative infant dose. It describes what percentage of the mother's dose — adjusted for body weight — would reach the child. As a rough orientation, values below roughly 10 per cent are generally regarded as harmless, and many well-studied substances lie well below one per cent.

4. Timing: making use of the longest gap between feeds

This is the section that makes the biggest difference in everyday life. The concentration of a substance in the blood — and therefore in the milk — is not constant: it rises after the dose, peaks after one to three hours and then falls again. So the dose can be placed in such a way that the peak does not coincide with a feed.

1. Feed first, then swallow. Take the tablet immediately after putting your baby to the breast — that leaves the longest possible stretch until the next feed.
2. Find the longest gap. With one tablet a day: place it at the start of the longest break between feeds, often the last feed in the evening.
3. Tie several doses to the rhythm. With three doses a day, "always straight after feeding" works best — no clock arithmetic needed.
4. Place one-off doses deliberately. A single painkiller can almost always be timed so that two to three hours remain until the next feed. If a dose falls awkwardly, milk expressed in advance helps — a convenience, not an obligation.

Pump and dump: needed less often than many people think

"Pump and dump" persists stubbornly as the standard solution. It really only makes sense with a genuine short-term contraindication, for example after nuclear medicine investigations. With alcohol, expressing milk does not speed up the breakdown: the level in the milk follows the level in the blood. And after a routine anaesthetic or a usual dose of a painkiller, discarding milk is unnecessary.

5. Pain and fever: the agents of choice

The most common question of all — and the one with the clearest answer. Ibuprofen and paracetamol are regarded as the agents of choice for pain and fever while breastfeeding: in use for decades, and both passing into the milk only in very small amounts.^³

For choosing between them in an individual case, the Painkillers compared guide is worth reading. As a principle: the right medicine at an adequate dose for a limited time — not half a tablet out of a guilty conscience.

For more severe pain, the combination of the two standard medicines is usually exhausted first; opioids are prescribed sparingly by the treating practice and for as short a time as possible.

6. Antibiotics: almost never a reason to stop breastfeeding

A bladder infection, mastitis, tonsillitis — antibiotics are no rarity in the first year after birth. Most of the common antibiotics can be used while breastfeeding: penicillins such as amoxicillin are among the best studied active substances there are and are regularly prescribed to breastfeeding women too.

Cephalosporins, and depending on the situation macrolides, are also an option. Other groups are used more cautiously, because better studied alternatives exist. So do say when you are prescribed something that you are breastfeeding.

7. Colds and allergies: nasal spray, antihistamines, cough remedies

An infection is no reason to interrupt breastfeeding — on the contrary: through the milk your child receives antibodies. What helps against the symptoms is set out in the guide Cold, flu or covid. A few particulars apply while breastfeeding:

Decongestant nasal spray

Sprays containing xylometazoline act locally in the nose; very little reaches the rest of the body. Used briefly, they are considered acceptable. The familiar trap remains: after a few days there is a risk of habituation — the background is under Nasal spray dependence. Sea water or saline spray is the alternative you can use without limit.

Antihistamines for allergies

With hay fever and itchy skin reactions, the newer, minimally sedating antihistamines are first choice: loratadine and cetirizine are well studied in breastfeeding. Older, strongly sedating substances are avoided, because they can make the child drowsy as well.

Cough and sore throat

Lozenges, inhaling saline solution and plenty of fluids are uncritical. Be careful with cold remedies that have "everything in them": they often contain several active substances, sometimes including exactly the ones you would want to avoid. Single-substance products have a clear advantage here.

8. Long-term medication: antidepressants and other continuing treatments

With a chronic condition it is not a matter of three days but of months. The good news: for most of the major indications there are options compatible with breastfeeding.

Antidepressants

A depression after birth is common and needs treating. Left untreated it puts a strain on bonding, sleep and coping with everyday life — that is not a "soft" risk. Within the SSRIs, sertraline is regarded as the best studied substance during breastfeeding; the amounts in the milk are usually very low. Data are available for citalopram as well, where the assessment is more differentiated.^¹

Other common long-term treatments

• Thyroid: levothyroxine replaces one of the body's own hormones and is unproblematic — with Hashimoto's the dose is often readjusted after the birth.
• Asthma: inhaled treatments act predominantly locally in the lungs; asthma should stay well controlled.
• Diabetes, high blood pressure, epilepsy: established options exist here as well — the choice is made by the specialist looking after you.

If you take several preparations on a long-term basis, you should also keep an eye on possible interactions.

9. What really is critical

Honesty is part of this: there are situations in which a break from breastfeeding, or stopping altogether, genuinely is considered. They are rare, but they are real.

Further situations in which a genuine weighing-up is needed:

• Cytotoxic drugs and immunosuppressants in cancer treatment: here breastfeeding is usually stopped, or a defined break is taken; the decision is made at the treating centre.
• High-dose iodine and radioiodine treatment: iodine accumulates actively in the milk. Radioiodine treatment requires a break from breastfeeding set by a doctor; iodine-containing contrast media and disinfectants are avoided as well.
• Nuclear medicine investigations: depending on the substance, a limited break is specified — one of the few cases in which expressing and discarding milk makes sense.
• Long-acting benzodiazepines: avoided, because they can cause poor feeding and drowsiness in the child.

10. The package leaflet paradox

You open the leaflet and read: "Should not be used while breastfeeding." And that sentence appears even for substances that embryotox explicitly lists as the agent of choice.

The explanation is unspectacular: the sentence is often legal protection, not a medical assessment. A positive statement would require licensing studies in breastfeeding women — and for ethical and practical reasons those are hardly ever carried out. Where such a study is missing, the manufacturer words it negatively as a precaution, even after decades of experience.^⁴

The reverse also holds: if there is no warning in it, that does not automatically mean "harmless" — it can also mean that no data exist. You may know the same pattern from the guide Medications during pregnancy. One thing is important: the assessments are not transferable — a substance that is critical in pregnancy can be unproblematic while breastfeeding, and the other way round.

11. Alcohol, smoking, caffeine — and your milk supply

Medicines are not the only things that pass into the milk:

These recommendations follow the guidance of the Nationale Stillkommission, Germany's national breastfeeding committee.^⁵ The basic stance remains: an everyday life that is less than perfect is no reason to stop breastfeeding. See also Medications and alcohol.

Keeping an eye on milk supply and on your child

Some substances can affect milk production — hormonal contraceptives, for instance, if they are started too early (see Medications and contraception). If your milk supply drops noticeably after starting a new preparation, that is something to raise at your next appointment — not a reason to panic.

• Watch three things in your child — feeding behaviour, alertness, bowel movements. Marked drowsiness or refusal to feed needs medical assessment.
• Keep a complete list — with the date of the first day of each medicine, and including over-the-counter products: Keeping a medication list. As soon as your child is given medicines of their own, separate rules apply: Medications for children.

12. How brite helps you while you are breastfeeding

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