Thrush: symptoms, causes & treatment

Thrush is a fungal infection in the mouth and throat, caused by the yeast Candida albicans. The medical term is oral candidiasis. Candida is present in 20 to 50% of the healthy population in small quantities in the mouth, without causing symptoms. Thrush only develops when the fungus overgrows, usually because the immune system is temporarily weakened or the oral microbiome is disrupted.

In babies and young children thrush is relatively common. Up to 4% of newborns experience it in their first weeks of life. In adults without underlying conditions, oral candidiasis is rarer, but it does occur with certain risk factors.

Thrush is bothersome and can lead to fussiness during feeding or reduced food intake in babies. In adults, it often causes a burning or painful sensation in the mouth. The good news is that thrush is almost always treatable, and symptoms usually disappear quickly after the correct treatment.

Candida albicans overgrows when the immune system is temporarily weakened or when the oral microbiome is disrupted. The fungus then has the opportunity to multiply unchecked.

Thrush in babies

In newborns, the immune system is still incompletely developed, making it easier for Candida to overgrow. Infection can occur during birth if the mother has a vaginal Candida infection, but also via a contaminated nipple, pacifier, or thumb-sucking. Breast milk contains milk sugars that can serve as a breeding ground for Candida, increasing the chance of overgrowth.

Thrush in adults

In adults, underlying risk factors play a role. The most common include: broad-spectrum antibiotics (because competing bacteria are killed, Candida is given free rein), inhaled corticosteroids for asthma (if the mouth is not rinsed after use), diabetes mellitus, HIV/AIDS or other immune-suppressing conditions, chemotherapy, poorly cleaned dentures, smoking, and Down syndrome. Chronic stress and exhaustion can also weaken the immune system enough for thrush to develop.

The most characteristic sign of thrush is white, cheese-like or creamy patches on the mucous membranes of the mouth: on the tongue, inside of the cheeks, or the palate. The key difference from ordinary milk residue in babies is that thrush patches cannot be wiped away with a wet cloth, whereas milk residue can. Beneath the white patches, the mucous membrane is red and sensitive.

Thrush or milk residue?

Gently wipe away the white patch with a wet gauze. If they come off easily, it's likely milk residue. If the patch remains, or if the mucous membrane underneath is red and damaged, this indicates thrush. A clicking sound during feeding is an additional indicator.

Thrush on the nipples

In breastfeeding mothers, Candida can also occur on the nipples. Characteristics include a burning or shooting pain in the nipples, even after feeding, and pink, shiny, or flaky nipple skin. When both the mother and the baby experience symptoms, it's important that both are treated simultaneously to avoid a ping-pong effect.

Is thrush dangerous?

In healthy babies and adults, thrush is a harmless condition that is easily treatable. In people with a severely weakened immune system, Candida can penetrate deeper, but this is rare with a healthy immune system. You can also find more information about similar conditions under other oral conditions.

In babies, thrush primarily affects the tongue, the inside of the cheeks, and the palate. In some cases, the infection spreads to the lips or throat. Thrush on the nipples (in the mother) is located on the nipple and areola.

In adults, the mucous membrane under dentures is a common location, especially when the dentures are not thoroughly cleaned daily.

Note an important safety tip. Never apply the treatment to the back of a baby's throat, but always apply the medication to the inside of the cheeks and tongue, and follow the practitioner's instructions carefully.

Besides thrush, there are also other conditions that cause mouth pain or mouth sores and require a different approach.

Thrush rarely disappears on its own and usually requires targeted treatment. The sooner treatment is started, the faster the symptoms will disappear.

Hygiene measures

In addition to medicinal treatment, hygiene measures are essential to prevent reinfection. Boil pacifiers and bottles for five minutes daily and replace them after treatment. Wash nursing pads and bras at 60 degrees Celsius and change bra inserts regularly. Wash your hands before each feeding. Do not freeze expressed milk during an active thrush infection, as Candida survives freezing and can become active again upon warming. If a partner or family member also has symptoms, it is best to have them treated as well.

Medicinal Treatment

Treatment varies by age and severity. For babies younger than four months, nystatin suspension is prescribed. For babies aged four months and older, miconazole oral gel is recommended. Always apply the medication to the cheeks and tongue, never to the back of the throat. For adults, miconazole gel or a systemic agent can be used. If both the mother and baby need treatment, start both at the same time.

When to See a Doctor?

Consult a doctor if there is no improvement after a week, if thrush returns more than three times a year, if a fever develops, if your baby has difficulty swallowing or drinking, or if the immune system is severely weakened. Through Skindr, you will receive advice within 48 hours from a certified dermatologist, without a referral or waiting room.

Not all tips circulating online about thrush are effective or safe. Freezing expressed milk during an active infection does not help, as Candida survives freezing and becomes active again upon warming. Home remedies like baking soda or salt water have no proven effect against thrush. Waiting it out is also not a good idea for babies, as thrush rarely resolves on its own in infants. For breastfeeding, treating only the child is not enough, because if the mother also has Candida on her nipples, it will lead to reinfection. Finally, never apply medication to the back of a baby's throat, as this poses a choking risk.

Is Thrush Dangerous?

In healthy babies and adults, thrush is harmless and easily treatable. With a severely weakened immune system, Candida can penetrate deeper, but this is rare. Treat it promptly to prevent discomfort.

How Long Does Thrush Last?

With the correct treatment, symptoms usually disappear within 7 to 14 days. Complete the full course, even if symptoms seem to disappear sooner.

How Do I Recognize Thrush in My Baby and Not Just Milk Residue?

Milk residue wipes away with a wet cloth; thrush does not. Thrush spots are firmly attached to the mucous membrane and also appear on the cheeks and palate, not just on the tongue.

Is Thrush Contagious?

Not classically contagious. However, Candida can pass back and forth between a breastfeeding mother and baby. Treat both simultaneously to prevent a 'ping-pong effect'.

Can thrush go away on its own?

In adults, sometimes, if the underlying cause is removed. In babies, thrush rarely goes away on its own. Treatment is recommended to avoid pain and feeding difficulties.

Can Skindr help with thrush?

Yes. Through Skindr, a certified dermatologist reviews your photos within 48 hours and provides personalized advice, without a referral from a general practitioner.

• Skindr dermatologists (medically reviewed)
• DermNet NZ - Oral candidiasis
• Thuisarts.nl - Thrush in babies (April 2026)
• EBPNet / NHG - Oral candidiasis guideline