Decorative image

Taking medicines

It's important to take medicines safely and follow the instructions carefully. Talk to your doctor, nurse or pharmacist if you have any questions.

Taking medicines at home is a common part of cancer treatment.

The medicines are much more likely to work if you follow the instructions about how to take them. But we know from research that many people don’t take them as they should.

How you take a drug by mouth can affect how much of it is absorbed into your body. So if you don’t take it as you should, less of the drug may reach your cancer.

What affects how medicines work

There are a number of factors that affect how a drug is absorbed and how well it works.

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 need to take different drugs at different intervals of time.

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

Drugs must be taken at regular times to make sure you have the right level of the drug in your body. If you forget or miss a dose it can take some time to get back to the right level.

This is the same for drugs that control symptoms or that treat your cancer. For example, painkillers work best if you take them regularly so that the drug level is maintained in your body and so keeps pain under control.  Cancer drugs work in the same way, maintaining the cancer drug levels allows them to act on cancer cells more effectively.

Everyone forgets to take tablets sometimes. What you need to do if you forget a dose depends on the medicine you are taking. Missing one dose is unlikely to be a problem. But missing a dose a couple of times a day, or a week for a daily tablet, could mean the treatment doesn’t work as well as it should.

Tell your cancer doctor or specialist nurse if you have missed several doses in a row.

It is important to keep taking a drug for as long as your doctor 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.

Treatment cycles

You take some cancer medicines in treatment cycles. This means that you take the drug for a set period of time, followed by a break, also for a fixed period of time. 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.

It is important to remember to take the cancer medicines exactly as you have been told to. The break from treatment is important too. For many cancer drugs, it allows your body to recover.

For drugs to work, they must be broken down and absorbed into the body. When you take medicines by mouth as tablets, capsules or liquids, this process happens in the gut.

Some drugs are better absorbed on a full stomach and some on an empty stomach. If there are particular instructions about this your doctor, nurse or pharmacist will tell you. It will also be on the information sheet you get with your tablets and on 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 interferes with a number of drugs. This information will be part of the instructions you get with your drugs.

Check with your doctor, nurse or pharmacist if you are not sure 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 cancer doctor or nurse if you have diarrhoea or are being 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 doctor about any other medicines you are taking, including vitamins, and alternative or complementary therapies.

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

Check with your cancer doctor, nurse or pharmacist before you take any medicines that you have bought yourself.

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

You might be used to keeping medicines in the bathroom cabinet. But because the temperature varies a lot 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.

Problems with taking medicines correctly

There are many reasons why people don’t take medicines as they’ve been told to.

Understanding how to take your medicine

We know from research that people sometimes don’t understand exactly how to take medicines, or the instructions are too complicated. Ask your doctor, nurse or pharmacist to explain again. It might help to ask them to write it down.

It's also important to understand why you are taking a particular medicine and what it will mean if you don’t take it. If you don’t understand why you are taking a particular medicine you are less likely to carry on taking it.

Difficulty swallowing tablets or opening packets

You might have difficulty swallowing tablets, or can’t open the bottle. Let your doctor, nurse or pharmacist know. Some drugs are available as liquids or you can have them in a different type of container.

Side effects

Some people may stop taking a drug if they find the side effects difficult to cope with.

Side effects can often be controlled so let your doctor or nurse know if you have them. They can look at ways of helping you cope with any problems.


There are a number of things you can do to make sure you are taking your medicines as you should.

Finding out about your medicines

Find out why you are taking each drug. If you know what it’s for and how important it is, that will help you to remember.

You also need to know:

  • how you should store it
  • how long you will be taking it for
  • what the side effects are and who you can contact if you have any problems
  • what to do if you miss a dose

Make sure you know how you should take each drug including:

  • what time to take it
  • whether you can take it at the same time as other drugs
  • when to stop taking the drug
  • whether you need to take it with a full or empty stomach

We all forget to take medicines sometimes. It can help to write down when you need to take them, along with any instructions you need to follow.

Using a pill box

If you have several different tablets to take, a pill box can be helpful. These are divided into smaller boxes for each day of the week. There are compartments for different times of the day. 

You fill the box up once a week with your tablets or you can get someone to do it for you.

The boxes are sometimes called monitored dose boxes and can be bought from most pharmacies. The pharmacist will be able to offer advice.

Setting an alarm

There are different ways that can help you remember to take your medicine on time, such as:

  • setting an alarm on your watch, clock or mobile phone
  • downloading a reminder app on your mobile phone

Making a chart

You could make a chart with all your drugs and drug times listed to help you remember if you have taken your medicines. This can be helpful if you're taking more than one medicine a day. You or your carer can tick off the medicines as you take them.

Information and help

Dangoor sponsorship

About Cancer generously supported by Dangoor Education since 2010.