Cancer and taste changes

Alterations in taste and smell are among the most difficult side effects of cancer treatment¹. They take the pleasure out of mealtimes and can prevent you from eating  what you need, causing unintentional weight loss and even malnutrition. Read on to learn about the common taste changes, how they affect your body’s ability to cope with cancer, and what you can do to combat these changes.

How common are taste changes in cancer?

Sensory changes like taste and smell changes are extremely common, affecting up to 70% of people with cancer during treatment². They can occur in any form of cancer but are particularly frequent in patients with head and neck cancer³. In addition to taste changes, people with cancer may experience changes in their sense of smell and “mouthfeel” (how food or drink feel in the mouth)⁴. Taste and smell alterations generally appear shortly after patients begin treatment and may last for 6–12 months after treatment ends, sometime longer^2,5.

What type of taste changes may happen?

Cancer and its treatment can affect taste in many ways³. You may find that your sense of taste generally decreases, so that flavors aren’t as strong as they used to be. Conversely, flavors may be heightened, making everything taste more sweet, sour, salty, or bitter than before. Your sense of taste may be altered so that food tastes different, and you may develop a new dislike of particular foods. You may also have a strange or unpleasant taste in your mouth. Occasionally, people lose their sense of taste entirely³.

Why do I have a metallic taste in my mouth?

Having a metallic taste in the mouth is very common among people with cancer. Studies have found that as many as 78% of patients being treated with chemotherapy, radiotherapy, or targeted therapy have a metallic taste or find that food tastes metallic⁶. People with this particular side effect are also likely to report having a bitter taste in their mouth or an increased sensitivity to sour or bitter foods⁶. As well as a metallic taste, treatments for cancer may cause a “rancid” or “chemical” taste in the mouth. Fortunately, these side effects typically disappear after treatment ends².

What causes taste changes in cancer?

You perceive flavor via around 5000 taste buds on your tongue and inside your mouth. The taste buds contain special cells, called receptors, which detect the basic tastes of sweet, sour, salty, bitter, and umami^2,3. Sometimes, taste changes are caused by the cancer itself interfering with the body’s normal processes^2,3. More often, however, taste changes are an unintended side effect of cancer treatment. Both radiotherapy and chemotherapy damage the tastebuds, affecting how food and drink taste; they can also affect the sensory nerves, changing how things feel in the mouth^2,3. Surgery for cancer may also affect taste and smell if it involves damaging parts of the mouth, tongue, or nose.

Why can cancer cause a dry mouth?

Treatments for cancer – particularly chemotherapy and radiotherapy – can cause a dry mouth by reducing the amount of saliva you make. Because saliva helps the tastebuds to perceive flavor, having a dry mouth can affect your sense of taste. It can also cause other problems, such as mouth infections, a sore throat, and even tooth decay^2,3.

Why do taste changes matter?

Changes in your sense of taste and smell matter because they interfere with the enjoyment of eating and drinking. People with taste changes tend to avoid certain foods and eat and drink less than normal – meaning that their body doesn’t get all the nutrition it needs^4,5. Taste changes lead to a 20–25% reduction in daily energy intake, resulting in weight loss – a particular concern in cancer^4,5. Without adequate nutrition, your body will be less able to cope with both the cancer and its treatment, reducing the chance of a successful treatment⁷.

When should I see a doctor?

If you are struggling to eat and drink, notice unexplained weight loss, notice changes in taste or have concerns about your diet and nutrition, talk to your healthcare professional. Depending on the cause of your symptoms, your healthcare team may be able to help you with medication, dietary changes, and/or nutritional support. As many cancer treatments are long and complex, you may benefit from being referred to a dietitian who can work out an individualized nutrition plan.