What is a side effect?

All drugs used to treat cancer cause side effects. Side effects are unwanted things that happen to you as a direct result of medical treatment – in this case, taking a cancer treatment drug. It can sometimes be easy to confuse drug side effects with symptoms of the cancer. Symptoms are the things that happen to you as a direct result of the cancer and are not due to your treatment. Treatment may shrink your cancer and make your symptoms better.

Different drugs have different side effects – for example, they don't all cause hair loss or sickness. There is information about the specific side effects of many chemotherapy drugs in this section of CancerHelp UK. The side effects are divided into common, occasional and rare for each drug. Ask your doctor to write down the names of your drugs so that you can look each one up.

The side effects of each drug vary for different people though. Some people find that they get only very mild side effects. You may get one, two or a few side effects of a particular drug. It is not possible to say beforehand whether you will have a particular side effect, when the effect will start or stop, or how bad it will be for you. These issues depend on many factors including

• Which drugs you are having
• How long you have been taking the drug
• Your general health
• The dose (amount of drug)
• The way you have the drug (for example, as a tablet or injection)
• Other drugs or cancer treatments that you are having

• Some side effects are serious medical conditions that need to be treated
• Some side effects are inconvenient or upsetting but are not harmful to your health
• Discuss your side effects with your doctor or nurse – often they can be reduced
• Phone your cancer hospital and speak to a cancer specialist doctor or nurse urgently if you are worried about a side effect
• Most side effects don't do any lasting harm and will gradually go away after your treatment finishes
• If you don't get side effects, it does not mean that your treatment isn't working

A system allows doctors to report any side effects of drugs to the government's drug safety watchdog. The safety organisation is called the MHRA (the Medicines and Healthcare products Regulatory Agency). The safety system is called the Yellow Card Scheme. This scheme helps to monitor drug safety by collecting information about new or suspected side effects or drug reactions. Until recently only health care professionals could report side effects. But now patients can also report side effects to MHRA using the Yellow Card Scheme. There is information about reporting through the Yellow Card Scheme on the MHRA website. But remember, it is important to contact your doctor if you are worried about side effects from any drugs you are taking or have recently been been taking.