Oral Thrush in Babies

When to get help

See a GP if your baby is under 4 months and has signs of oral thrush. That is the NHS's line, and it exists because the pharmacy treatment is only licensed from four months.

See a GP too if you have treated thrush with a mouth gel and there is no improvement after a week, or if there is difficulty or pain when swallowing.

Seek urgent advice — NHS 111 in the UK (call rather than use the website for a child under 5), the GP out-of-hours service in Ireland, your paediatrician in the US or Canada, healthdirect on 1800 022 222 in Australia, Healthline on 0800 611 116 in New Zealand — if your baby is refusing feeds, has fewer wet nappies than usual, or shows other signs of dehydration such as a sunken soft spot, sunken eyes or no tears when crying. A sore mouth that stops a baby feeding is a fluid problem before it is anything else.

Call emergency services — 999, 112, 911, 000 or 111 by country — for the universal baby red flags: a rash that does not fade under a pressed glass, laboured breathing, a first seizure, blue, grey or mottled skin, or a baby who cannot be roused. Thrush does not cause any of those, which is exactly why they override it.

What it looks like in a baby

The NHS description is short and precise. A baby with oral thrush will have a white coating on their tongue. It may look like cottage cheese and it cannot be rubbed off easily. Sometimes there are white spots elsewhere in the mouth. Babies with oral thrush may not want to feed.

In adults the picture is different — a mouth that is red inside with white patches that leave red, sometimes bleeding spots when wiped off — which is worth knowing if you are breastfeeding and wondering about your own symptoms.

Thrush or milk?

This is the question almost everyone arrives with, and the answer is in the NHS wording: thrush cannot be rubbed off easily. Milk residue on a tongue wipes away with a clean damp finger or a soft cloth, leaving normal pink tongue underneath. Thrush stays put, and if it does come away it tends to leave a red or sore-looking area.

Two other clues. Milk residue is usually confined to the tongue and appears right after a feed; thrush often appears in patches on the inside of the cheeks, gums or roof of the mouth as well, and persists between feeds.

What causes it

Oral thrush is an infection caused by a fungus called Candida. The NHS notes that certain things can make the fungus grow more than usual, including taking antibiotics over a long period, using inhalers, and cancer treatment such as chemotherapy. In babies, a recent course of antibiotics is the most common identifiable trigger, but in many cases there is no obvious cause at all — Candida is a normal inhabitant of the mouth, and a young immune system simply lets it overgrow.

The NHS also notes that oral thrush in adults is not contagious. That is not a statement about babies and nipples during breastfeeding, which is a separate situation and worth raising with a midwife, health visitor or GP if feeding has become painful.

Treatment

Oral thrush can be treated with a mouth gel bought from a pharmacy. The NHS states the gel is suitable for adults, children and babies over the age of four months. Ask your pharmacist for advice and always follow the instructions on the packet.

Under four months, the NHS says see a GP rather than treating it yourself. Do not use a gel licensed for older babies on a young one on the assumption that a smaller amount will do; the age limit is not about quantity.

If there is no improvement after a week of treatment, go back. Persistent thrush that does not respond is worth a second look rather than a second tube.

What to sterilise, and why

The NHS lists two hygiene measures under prevention that apply directly to babies:

• sterilise dummies regularly;
• sterilise bottles after each use.

Both are places where Candida can survive and be reintroduced to the mouth after treatment. Teats, dummy shields, the parts of a breast pump that contact milk, and any teething toys that go in the mouth are worth the same treatment while thrush is being treated. Reinfection from equipment is the usual reason a course of gel seems to work and then the patches return.

Feeding through it

A sore mouth can make a baby fussy at the breast or bottle, pull off repeatedly, or refuse altogether. Keep offering, offer smaller feeds more often, and watch nappies rather than volumes — output is the measure that tells you whether intake is adequate. If your baby was previously feeding well and has stopped, that is a reason to call an advice line the same day rather than waiting for treatment to work.

Mouth care beyond thrush

The NHS's general prevention advice includes brushing gums and tongue with a soft toothbrush in people without teeth, and rinsing the mouth after taking medicine. For a baby, the practical versions are gentle cleaning of gums once teeth start arriving, and offering a little water after any medicine that contains sugar or a steroid inhaler if one has been prescribed. None of this treats an active infection, but it reduces the chances of a repeat.