If a child is struggling to breathe, is floppy or will not wake, or their skin, lips or tongue look blue or grey: call 999 now. Colour changes are harder to see on brown and black skin, so check the palms, soles, lips and tongue. If you are worried but it is not an emergency, call NHS 111. In Northern Ireland use your GP out-of-hours service.

MarionSleep help for families

Growth, allergy and restless legs

Weight, suspected allergy, and what we will not claim about iron.

The short version

  • Call 999 if lips, mouth, throat or tongue suddenly swell, or breathing is very fast or a struggle. Use an adrenaline auto-injector immediately if available.
  • Weight charts are more forgiving than they look: moving one centile line is normal variation. Crossing two is worth raising with your health visitor.
  • Cow's milk allergy can be delayed: symptoms from two hours after a feed, up to 72 hours. Allergy UK's helpline is 01322 619898.
  • Eczema, colic, reflux and loose nappies are common anyway, so milk allergy is one possible explanation. A GP or health visitor sorts one from another.
  • For persistent leg discomfort at night, see your GP. We are not printing iron targets or supplements, because no UK paediatric guidance stands behind them.

The rest of this page explains where this comes from. You do not have to read it tonight.

About 2 minutes to read

Weight and growth

Weight charts are more forgiving than they look. The centile lines show average gain, and moving by one centile line is normal variation. It is crossing two centile lines that the NHS says is worth discussing with your health visitor. Babies usually regain their birthweight by about 3 weeks, so ask for support if your baby loses a large amount of weight or has not regained it by then.

Frequent weighing does not catch problems sooner: the NHS suggests no more than monthly up to 6 months. Faltering growth also appears in the sleep apnoea and reflux lists above, which is part of why it is taken seriously.

Suspected allergy

Allergy UK divides cow's milk allergy into two kinds, separated by timing. IgE-mediated allergy is immediate, within minutes or up to two hours. Non-IgE-mediated allergy, the more common type, is delayed: from two hours after a feed, and it can take up to 72 hours. That delay is why it is easily missed.

Symptoms fall into four groups: skin (hives, eczema, redness, itching); digestive (vomiting, diarrhoea, tummy pain); breathing (sneezing, runny nose, coughing, wheezing); and general (fussiness, irritability, refusing to feed).

Allergy UK is honest about the catch here, and so are we: eczema, colic, reflux and loose nappies are common in babies generally, so milk allergy is only one possible explanation. A GP or health visitor taking an allergy focused history is what sorts one from the other. Allergy UK's helpline is 01322 619898, a geographic number at your normal call rate.

Anaphylaxis: call 999

  • lips, mouth, throat or tongue suddenly swelling
  • breathing very fast, or struggling to breathe
  • the throat feeling tight, or struggling to swallow
  • skin, tongue or lips turning blue, grey or pale
  • sudden severe confusion or drowsiness, or loss of consciousness
  • in children, going limp or unresponsive

Use an adrenaline auto-injector immediately if one is available.

Restless legs and iron

The link between low iron and restless legs is well described in adults, and the NHS restless legs page connects the two. We could not find any UK source linking iron deficiency to restless legs or disturbed sleep in children. So: if your child has persistent leg discomfort at night, take it to your GP. We are not printing a blood test target or suggesting iron supplements, because no UK paediatric guidance stands behind either.

Where this comes from

  • NHS (nhs.uk) bronchiolitis, sepsis, croup, colic, anaphylaxis, fever and baby weight guidance, for the 999 and 111 criteria, croup, colic, the crying advice and the centile rule. These pages are cited by name; we have linked the ones whose exact addresses we hold.
  • NHS, reflux in babies, for posseting, the timescales and the instruction not to raise the head of the cot or Moses basket.
  • Great Ormond Street Hospital, obstructive sleep apnoea, for the child-specific signs, the 1 to 3% figure, risk groups and the overnight sleep study.
  • ICON, the UK infant crying programme, for the crying curve, the four ICON messages and the walking-away instruction.
  • Cry-sis, for the helpline number and hours and the average two hours of crying a day.
  • The Lullaby Trust, Baby Check app, for the 17 checks for babies under six months.
  • The Sleep Charity, National Sleep Helpline, for the hours, the age limits and what the service cannot cover.
  • Sheffield Children's Sleep Service and the GOSH Respiratory Sleep Unit, for how tertiary sleep services take referrals.
  • NHS, postnatal depression and Samaritans, for the parental crisis red flags and the 116 123 line.
  • Allergy UK, for the IgE and non-IgE timings, the symptom groups, the over-attribution caveat and the 01322 619898 helpline.
  • NICE guidance on referral for snoring and for autistic children, reproduced second hand: nice.org.uk blocks automated checking, so we have avoided quoting any threshold from it.

Last checked 1 August 2026. This page is general information, not medical advice. If you are worried about your child, speak to your health visitor or GP.