What To Do After a Slip Up – Breastfeeding With CMPA

I’m slowly trying to work my way through creating posts that answer some of the most frequently asked questions that I see come up in my Breastfeeding With CMPA and Other Food Allergies Support Group on Facebook. You can already find lots of resources about going dairy free and breastfeeding a baby with CMPA on my website, including information on may contains, the milk ladder, alternative milks, and where to find the best dairy and soya free treats, and today I want to talk about something I see mums asking about often – what to do (and not do) if you slip up.

What is ‘a slip up’?

A slip up is generally when either mum or little one is accidentally exposed to dairy, or one of their other allergens. It’s one of those things that can and does happen unfortunately – whether a family member has misunderstood what foods need to be avoided, a restaurant has made a huge mistake, someone forgot to check the packaging or another mistake has been made.

First Steps After a Slip Up

The first thing to do once you realise you’ve slipped up is to remain calm and try not to panic. People either realise they’ve had a slip up straight away, or they realise once the reaction has begun.

If you realise straight away

If you’ve just realised you have eaten/your child has eaten something containing a food you need to avoid, the first thing to do is obviously remove the food from your child’s reach. Depending on your child’s previous reactions you will need to keep a close eye on them in case of an immediate reaction. If you have already confirmed your child is non IgE this will be less of a concern, but it’s still wise to be vigilant. If you have been prescribed antihistamines or an epi pen then keep these close to hand and refer to your action plan if you have one.

I’ve seen lots of mums who have been tempted to make themselves vomit after realising they’ve eaten something they shouldn’t, but this absolutely will not help and is not wise to do. It could cause harm, and there’s no guarantee that you’d be able to rid yourself of the allergen completely any way, so it’s kind of pointless.

If you see a reaction and realise you’ve slipped up

You may notice that your child is reacting, and begin to think back/ask questions to figure out where you’ve slipped up. If you can determine what it was and when you ate it that may be helpful, but sometimes these things are so hard to pinpoint. Also worth remembering that things like viruses can cause hives, and bugs/colds/teething and developmental leaps can often cause symptoms similar to an allergic reaction.

Should I still feed my baby?

I understand completely when mums contemplate pumping and dumping, and feeding their baby formula or previously expressed milk once they learn their milk may be contaminated, but again it’s not a great plan of action for breastfeeding mums. We have no way to tell when your milk may become ‘clean’ or ‘free from’ again, so absolutely no way to assess when it would be ‘safe’ to get baby back to the breast again. As well as that, going days (or longer) without feeding baby at the breast risks damaging your supply and your breastfeeding relationship.

Using formula introduces plenty of risks of its own, which many mums are keen to avoid. Breast milk will actively help your baby’s gut to heal following a reaction, as well as providing much needed nutrients and comfort. When considering whether or not to continue to breastfeed through a slip up or reaction – the pros always outweigh the cons.

Also – if you have yet to challenge the CMPA and confirm the allergy, you’re certain that you have consumed a portion of dairy and you see a clear reaction then you can consider this slip up the challenge that you would’ve needed to do at 6 weeks dairy free any way.


I know how easy it is to beat yourself up when something like this happens. The guilt that you’ve caused your baby pain is such a hard thing to deal with, but these things can (and do) happen to many of us and you have to carry on. As above, if you’ve not already confirmed the CMPA then it’s something you would’ve gone through any way, and it is sometimes just a part of allergy life. It’s tough but it will be okay, and you’re still doing an amazing thing for your little one.

How long will the reaction last?

This is really an impossible question, and not one I can answer because it depends so much on the individual child and other variables – what were they exposed to (baked milk vs something like a yoghurt?), how much did they ingest… Reactions differ so much between children, and you may or may not know what a typical reaction looks like for your child. On a personal level, up until Dil was 3 he had never ingested dairy directly – so I would’ve had no idea what a ‘typical’ reaction would’ve been for him. His last reaction to soya through my breast milk lasted for well over a week.

Remember, a non IgE reaction can be within 72 hours of exposure. Delayed symptoms may continue to worsen over the following few days. Symptoms like diarrhoea or eczema may take a little longer to present, and may take a little while longer to resolve. Mucous may be present in their stool which usually indicates that the gut is starting to heal after being damaged – so this may continue for a week or more.

If you ever feel concerned or if you see something that is unusual for your baby then don’t hesitate to reach out to your GP/HV/dietitian and get them checked out. Obviously any difficulties with breathing or swallowing, any wheezing or swelling needs urgent medical attention. If you see a large amount of blood in their nappy you may also want to go get some medical advice.

What can I do to help my baby during this time?

Feed, feed, feed. As above breast milk and the act of breast feeding will provide some much needed comfort for your child, as well as providing them with lots of nutrients which they’ll probably be very in need of if they’ve been throwing up or unwell.


Depending on your child’s age you may have been prescribed something specific for them or you may have bought something over the counter. Antihistamines like Piriton are for IgE reactions and may reduce swelling and itching, but will not help with delayed reactions and should not be used in that case. If you believe your child is in pain you may consider using something like Calpol, but this won’t always be necessary. Again if in doubt reach out to a medical professional or visit your local pharmacy.

What if they don’t react?

If you suspect there has been a slip up, either through breast milk or directly, and you haven’t seen a reaction then here are some things to consider before getting your hopes up:

  • Are you absolutely certain there’s been a slip up? Is it possible that actually you didn’t consume the allergen? It is possible that your little one touched the food but didn’t eat it? Etc
  • Has it been 72 hours yet? A non IgE reaction will take place within 72 hours of exposure, and we estimate it would take about 4-6 hours for an allergen to be ingested by you and then reach your breast milk. If it hasn’t been 3 days yet then continue to wait, and keep a close eye on your little one.
  • Is it possible that the amount you/your little one consumed was too small to cause a reaction? If you consumed a very small amount of the allergen (say a mouthful of the wrong tea for example) it’s possible that this, then filtered through breast milk, would be too small to cause much of a problem for a lot of little ones.

If they definitely consumed the allergen, it’s been 72+ hours, you’re confident it was a decent amount and there has been no reaction then you do need to consider whether or not your little one has outgrown their allergy. If it was an indirect slip up (through you) then it’s possible it wasn’t enough exposure to cause a reaction in this instance. Either way, it’s a great sign and you could consider planning a milk ladder attempt if that’s appropriate for your circumstances (have a read of this post to determine that). I would always want to discuss this with a dietitian first though.

Hopefully that helps answer some of the questions that come up when you’ve experienced a slip up, and put your mind at ease about continuing to breastfeed because that really is the most important thing. As always if you have any more questions or if I’ve missed something useful then please leave a comment below and I will get back to you! For more information and advice don’t forget to follow my Facebook page and join my Breastfeeding With CMPA Support Group.

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