Can I breastfeed after a CT or MRI scan with contrast?

The verdict

You can feed normally, before the scan and after it. Neither the contrast used for CT nor the contrast used for MRI requires you to stop breastfeeding or to throw milk away.

The Royal College of Radiologists and the Society of Radiographers issued a joint statement on this in January 2022. On CT it is unambiguous: cessation of breast feeding or expression and discarding of breast milk after iodinated contrast media administration are not required. On MRI it says that while no special precaution or cessation of breastfeeding is required, the continuation or cessation of breastfeeding for twenty-four hours should be at the discretion of the lactating mother in consultation with the clinician. Its overall position is that patients who wish to continue breast feeding after being administered with contrast agent should be able to do so, as there is no evidence of risk to the baby or child.

Note what that MRI sentence does and does not say. It does not recommend a twenty-four hour break. It says no break is required, and that if a mother wants one anyway, that is her call to make with her clinician. That is a very different thing from an instruction.

Why the amounts are negligible

Two barriers sit between the injection and your baby, and both have to be crossed for anything to matter.

The first is transfer into milk. Only a very small fraction of an injected contrast agent enters breast milk. LactMed describes intravenous iodinated contrast media as poorly excreted into breast milk, and for gadolinium-based agents it describes the amount excreted into milk as a fraction of a percent of the quantity that would be given to an infant directly.

The second is absorption from the gut. Both classes of contrast are designed to stay in the bloodstream and be excreted by the kidneys, and neither is well absorbed when swallowed. LactMed states that these agents are poorly absorbed orally and are therefore not likely to reach the bloodstream of the infant or cause adverse effects in breastfed infants.

Multiply a tiny transfer by almost no absorption and the exposure becomes theoretical rather than real.

Where the twenty-four hour myth came from

Older European guidance suggested an optional twenty-four hour interruption after certain gadolinium agents, particularly those that release more free gadolinium. LactMed records that some European guidelines have recommended this, while guidelines developed by North American professional organisations state that breastfeeding need not be disrupted after a nursing mother receives a gadolinium-containing contrast medium.

That historical split is why you may still be handed a leaflet, or told by a member of staff, to express and discard for a day. It is not the current UK position. If you meet that advice, the RCR and SoR statement is the document to ask about.

The one real exception: nuclear medicine

Contrast is not the same as radioactivity, and this is the distinction that matters most on this page. CT and MRI contrast agents are not radioactive.

Nuclear medicine studies are different. They involve giving a radioactive tracer, and some tracers do require a defined interruption of breastfeeding or, rarely, permanent cessation. The Academy of Breastfeeding Medicine's protocol on radiology and nuclear medicine studies in lactating women sets out which agents need what, and the interruption depends entirely on the isotope used. If your scan is described as a bone scan, a thyroid scan, a lung perfusion scan, a PET scan or anything involving a radioactive tracer or radioiodine, ask specifically about breastfeeding, because the answer is agent-specific and is not covered by the contrast guidance above.

Planning the appointment

Tell the radiology department you are breastfeeding when you book, not when you arrive. It costs nothing and it heads off a leaflet-driven argument in the waiting room.

Feed or express immediately before you go in. That buys you comfort and gives your baby a full feed regardless of how long the department takes.

Take a pump if you are likely to be waiting a long time, and take expressed milk if someone else will be with the baby. Neither is required by the contrast, only by the logistics.

Contrast injections can make you feel warm or flushed, and you may be asked to drink extra fluids afterwards to help clear it. Drinking extra is sensible for you anyway while producing milk.

If you have already been told to discard

Do not panic and do not assume your supply is ruined. If you expressed and discarded for a day on the basis of old advice, keep expressing at the frequency you would normally feed, and go straight back to feeding. In the UK, the Breastfeeding Network's Drugs in Breastmilk service and its factsheet on MRI scans will confirm the current position in writing if you need it for a clinician.

Where guidance differs

This is one of the few areas in this batch where a genuine international split existed, and where the residue of it still produces conflicting advice.

The UK, through the Royal College of Radiologists and the Society of Radiographers, states that cessation of breastfeeding or discarding milk after iodinated contrast is not required, and that no special precaution is required for gadolinium, with any twenty-four hour pause being the mother's choice rather than a recommendation.

North America, through radiology and breastfeeding bodies, states that breastfeeding need not be disrupted after either class of contrast.

Older European guidance suggested an optional twenty-four hour break for some gadolinium agents, and this is the source of most conflicting leaflets still in circulation.

Australia, through the Australian Breastfeeding Association, advises that x-rays and scans do not generally require breastfeeding to stop, with nuclear medicine handled separately.

Everyone agrees on the exception: radioactive tracers are a different question and need an agent-specific answer.