Taking medicines

Drugs stay active in the body for a particular length of time, from a couple of hours to over a day. This is why you must take different drugs at different intervals.

The time it takes for the body to absorb a drug and be most effective also varies.

You must take your medicine regularly to ensure you have the right level of the drug in your body. If you forget or miss a dose, it can take time to get back to the right level.

This is the same for drugs that control symptoms or treat cancer. For example, painkillers work best if you take them regularly. This way, the drug maintains its level in your body and controls pain. Cancer drugs work in the same way. So, if you maintain the cancer drug levels, it will act much better on cancer cells.

Everyone forgets to take tablets sometimes. What you need to do if you forget a dose depends on your medicine. Missing one dose is unlikely to be a problem. But missing several doses could mean the treatment doesn’t work as well as it should.

Tell your cancer healthcare team if you have missed several doses.

It is important to keep taking a drug for as long as your healthcare team has told you to. This could be weeks, months or even years.

For example, the hormone therapy tamoxifen for breast cancer is a tablet you may take daily for 5 years. It reduces the risk of the cancer coming back.

For drugs to work, your body must break them down and absorb them. This process happens in the gut when you take medicines by mouth as tablets, capsules or liquids.

A full stomach absorbs some drugs better, and an empty stomach works better for others. Follow the instructions from your doctor, nurse or pharmacist about this. It will also be on the information sheet you get with your tablets and the label on the box.

Some foods affect how much of a drug you absorb, which could stop it from working as well as it should. For example, grapefruit and grapefruit juice interfere with several drugs. This information will be part of the instructions you get with your drugs.

Check with your doctor, nurse or pharmacist if you are unsure if you should take your drugs on an empty stomach or not.

Having diarrhoea or being sick might affect the amount of the drug that stays in your body. You might not be absorbing as much of it as you should.

Tell your healthcare team if you have diarrhoea or are sick. They need to know how your cancer treatment is being affected. And they will also be able to prescribe medicines to help.

Some drugs can affect each other, changing how much you absorb. Tell your healthcare team about any other medicines you are taking, particularly if you are taking vitamins and alternative or complementary therapies.

Supplements or therapies can interfere with how well medicines work. For example, St John’s Wort can affect how the body breaks down drugs. And laxatives can make a drug pass through your system more quickly.

Check with your healthcare team before taking any medicines you have bought yourself.

Like food, some drugs can go off. You need to keep some drugs in the fridge and others at room temperature. Follow any instructions about where and how you keep them.

Many people keep medicines in the bathroom cabinet. But because the temperature varies in bathrooms and the air may be damp, it's best not to keep medicines there.

All medicines have expiry dates. Always make sure any medicines you have are within the expiry date.

You take some cancer medicines in treatment cycles. This means you take the drug for a set period, followed by a break. For example, you might take a drug every day for a week and then not take it for 2 weeks. This 3 week period in total is one cycle of treatment.

Take your cancer drugs exactly as your doctor, specialist nurse or pharmacist has told you to. The break from treatment is important too. For many cancer drugs, it allows your body to recover.