Why is my tongue white after antibiotics?

Your mouth hosts a mix of bacteria and a small amount of Candida yeast. The bacteria compete with the yeast for space and nutrients, which keeps Candida at harmless levels. Antibiotics, especially broad-spectrum ones, cut back the bacteria without touching the yeast, and the yeast can multiply into visible patches.

The NHS lists taking antibiotics for a long time as a risk factor for oral thrush, DermNet lists broad-spectrum antibiotics, and Cleveland Clinic includes antibiotics among the medicines that can contribute. Mayo Clinic also notes that long-term antibiotic use can lead to a yeast infection that turns the tongue white.

The illness you were treating also plays a part. Fever, a blocked nose, eating less and drinking less all let an ordinary coating build up, separate from any yeast.

If you are unsure, a pharmacist can usually tell by looking. For a side-by-side guide, see thrush or white tongue.

• Do not stop your antibiotic because of a white tongue. Finish the course as prescribed unless your doctor tells you otherwise.
• Talk to a pharmacist. The NHS says oral thrush can often be treated with an antifungal mouth gel from a pharmacy, suitable for adults, children and babies over 4 months.
• See a doctor if a baby under 4 months has signs of thrush, if there is no improvement after a week of treatment, if swallowing is painful, or if you have a weakened immune system.
• Rinse your mouth after meals and medicines, and brush twice a day.
• Clean dentures daily and take them out at night.

Cleveland Clinic notes that home remedies such as saltwater rinses, yogurt or probiotics may ease symptoms but do not replace antifungal treatment. With treatment, thrush usually clears within one to two weeks.

A coating from being ill fades as you recover. Drink plenty, return to normal food when you can, brush twice daily and clean your tongue gently once a day. Our guide to white tongue when you are sick covers this in more detail. If gentle cleaning leaves the tongue red or sore, stop and treat it as possible thrush instead.

Thrush can happen to anyone after antibiotics, but sources list higher risk for:

• Babies and older adults
• People who wear dentures, especially if they are worn overnight or fit poorly
• People using steroid inhalers for asthma or COPD
• People with diabetes, a dry mouth, or a weakened immune system from illness or treatment
• People who smoke

If you are in one of these groups and need repeated antibiotics, ask your doctor whether you should watch for thrush or how to lower the risk.

Use antibiotics only when they are prescribed for you, and finish the course as directed. Keep up brushing and daily tongue cleaning while you take them, drink well, and rinse after doses of liquid medicine. If you use a steroid inhaler, rinse your mouth with water and spit, or brush your teeth, after each dose, as the NHS advises.