White patches in your mouth during chemo: recognising thrush

Call 911 if your throat swells so that breathing becomes difficult, or if you cannot swallow your own saliva.

Call your doctor or nurse immediately if you have a fever of 100.4 °F (38 °C) or higher while you are having chemotherapy. CDC gives that fever figure for mouth and throat problems during cancer treatment. CDC calls a fever during chemotherapy a medical emergency. It says to ring your doctor at once, at any hour. Your white cells may be too low to fight it. If you go to an emergency room, say straight away that you are on chemotherapy and have a fever.

Call your care team the same day if you have white sores in your mouth, difficulty swallowing, or pain in your mouth, lips or throat that makes it hard to eat, drink or sleep. MedlinePlus advises contacting your provider if you have thrush-like sores, swallowing difficulty, or these symptoms plus cancer treatment.

An infection in someone whose immune system is suppressed is not something to watch for a week.

MedlinePlus describes thrush as a yeast infection of the tongue and lining of the mouth. It is caused by overgrowth of a fungus called Candida.

Candida is not an invader from outside. It lives in and on most people harmlessly. What changes during chemotherapy is the balance. When the immune system is not policing things as usual, the fungus takes the opportunity.

The signs MedlinePlus lists are:

• White velvety sores in the mouth or on the tongue
• Bleeding when you brush your teeth
• Pain when swallowing

The white patches are the giveaway. They are not simply a coating on the tongue that wipes away with a toothbrush.

MedlinePlus lists people with weakened immune systems, naming HIV and AIDS and chemotherapy, among those at higher risk.

The other risk factors on the list are worth knowing because several of them stack up during cancer care:

• Recent antibiotic use, because antibiotics kill the bacteria that normally keep fungus in check
• Steroid medicines, which are part of many cancer regimens
• Diabetes with high blood sugar
• Ill-fitting dentures
• Poor health generally, or advanced age

If you have recently finished a course of antibiotics for another infection, and you are on steroids as part of your regimen, you have collected several of these at once. That is not bad luck or poor hygiene. It is arithmetic.

MedlinePlus says providers usually identify thrush through visual examination. Sometimes a sore is scraped so the cells can be looked at under a microscope. In severe cases, throat cultures may be taken.

This is one of the reasons to show someone rather than describe it over the phone. A clinician looking in your mouth can often tell in seconds.

MedlinePlus separates mild from more serious cases.

For mild thrush it mentions yogurt or acidophilus pills. For moderate to severe cases it lists antifungal mouthwash, lozenges, or oral medicines such as fluconazole.

Take this to your team rather than the supermarket. You are on cancer treatment, and drugs interact. Whether fluconazole is right for you, and whether it plays nicely with everything else you are taking, is a decision that needs your medication list in front of someone qualified to read it.

MedlinePlus states that oral thrush can be cured. That is a genuinely reassuring sentence and it is worth holding onto when your mouth is sore and you are already tired of setbacks.

It also says recurrence is possible in people who are immunocompromised. If your immunity stays low through several more cycles, thrush may return. Knowing that in advance means you can catch it early the second time rather than spending a week wondering.

NCI's guidance for cancer treatment recommends checking your mouth every day for sores or white spots. That single habit is what turns thrush from a fortnight of misery into a phone call on day two.

It also recommends a soft toothbrush after meals and at bedtime, and daily rinsing with a warm water, baking soda and salt mixture. Gentle, frequent and boring is the goal.

If you wear dentures, remember that MedlinePlus lists ill-fitting dentures as a risk factor. If yours have stopped fitting well, that is worth mentioning too.