Cancer drugs
There are different ways of having cancer drugs. These include:
tablets, capsules and liquids that you swallow
an injection under the skin or into the muscle
a drip or slow injection into your bloodstream (intravenously)
Find out more about injections and drips
During your treatment, you might also have supportive medicines such as anti-sickness, painkillers or medicines to relieve constipation. Supportive medicines work in different ways and come in different forms, such as:
lozenges or pastilles
suppositories, enemas and pessaries
patches
inhalers and nebulisers
drops
creams, gels and lotions
powders that you dissolve in fluid
tablets that are soluble, fizzy (effervescent) and chewable
Read more about medicines such as anti-sickness and painkillers in the coping physically section
You usually have cancer drugs, such as chemotherapy, as cycles over several months. A cycle means that you have a cancer drug or a combination of cancer drugs and then often have a rest to allow your body to recover.
For example, you might have some chemotherapy drugs as a drip over a day or two and then have some time with no treatment. The treatment and rest time make up one treatment cycle. When you get to the end of the cycle, it starts again with the next cycle. A series of cycles is called a course of treatment.
There are some treatment cycles that mean you have treatment every day.
A treatment cycle and the course of treatment depend on several things. These include the:
type of cancer
of the cancer
types of drugs that you’re having
side effects the drugs might cause
time you’ll need to recover from side effects
Treatment cycles vary in length. This depends on the drugs and your treatment plan. Some treatment cycles are quite complicated.
Examples of a treatment cycle can be 14 days (2 weeks), 21 days (3 weeks), 28 days (4 weeks) or longer.
An individual treatment may last from a few minutes to a few days, if you are having it as an injection or drip. This will depend on the drug or combination of drugs you are having.
For example, the chemotherapy regimen doxorubicin and cyclophosphamide is a 21 day cycle. You only have these drugs on day 1. Then you have no treatment on days 2 to 21.
On day 1 you have doxorubicin as an injection or as a drip into your bloodstream over about 15 minutes. You also have cyclophosphamide as an injection or as a drip into your bloodstream over about 30 minutes.
Another example is osimertinib that you have as a 28 day cycle (4 weeks). With this treatment you take osimertinib once a day on everyday of your cycle of treatment. You do not have days without treatment.
There are more complicated treatment cycles where you have cancer drugs on several days and for different lengths of time. And the cancer drugs in the cycle might change as you go through the treatment.
How you take a cancer drug by mouth can affect how much your body absorbs. This means if you don’t take it as you should, less of the drug may reach your cancer, affecting how well it works.
Cancer 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 times.
The time it takes for the body to absorb a drug and be most effective also varies.
You must follow the instructions of when to take your drug to make sure 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. If you maintain the cancer drug levels, it will act much better on cancer cells.
This is the same for drugs that control symptoms. For example, painkillers work best if you take them regularly. This way, the drug maintains its level in your body and controls pain.
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.
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.
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.
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 being sick. They need to know how your cancer treatment is being affected. They can also usually prescribe you medicines to help.
Only take the amount (dose) you have been prescribed, not more or less.
Take your cancer drugs at the right time.
Take the drug for as long as your healthcare team has told you to. This could be days, weeks, months or even years.
If you forget and miss a dose, speak with your healthcare team. Don't take a double dose of the medicine.
If you feel sick or are unable to take your medicines due to side effects, let your healthcare team know.
Do not stop your cancer drugs unless you have talked with your doctor or pharmacist. Some treatments such as can cause side effects if you stop them suddenly. This depends on how much you are taking and for how long. Some steroid doses need to be lowered gradually before you can stop them.
Everything you take by mouth, including food, drink and medicine, needs to be absorbed by the body. This process happens in the digestive system.
A group of enzymes called cytochrome P450 (CYP450) are an important part of the process of how drugs break down in the body after they are absorbed into the blood. Most of these enzymes are made by the liver.
There are more than 50 CYP enzymes. The following enzymes are responsible for breaking down 90 out of every 100 (90%) drugs in the body:
CYP3A4
CYP2D6
CYP2C9
CYP1A2
CYP2C8
CYP2C19
The amount of these enzymes in the body can affect how quickly a cancer drug is broken down. This may change how well the drug works and the side effects you experience.
If too much of the cancer drug is broken down it might not work as well, and you might need a bigger dose which could cause more side effects. If too little of the drug is broken down, you could have bad side effects from the cancer drug and you might need a smaller dose.
Food, drinks and other drugs, including herbal supplements, can affect the level of CYP enzymes in the body. So while you are taking certain drugs, your healthcare team may tell you to avoid some foods, drinks or herbal supplements. You may also read this in the drug information sheet that comes with your cancer drugs or other medicines. Check with your doctor or pharmacist if you’re not sure.
The foods that are best known for affecting CYP enzymes are grapefruit and Seville oranges. This includes their juice and other products mostly made from these, for example, marmalade.
Other fruit juices that can cause interactions with some cancer drugs include:
pomegranate juice
pomelo juice
cranberry juice
grape juice
The food and drink you may need to avoid depends on the drug you are having and which CYP enzymes are involved. Your doctor or pharmacist will tell you if you need to avoid particular food or drink while on treatment.
There are many different types of drugs that can affect the CYP enzymes. These include:
some drugs
some antibiotics and antifungal drugs
treatment
medicines to stop seizures (fits). These are called anti-seizure medicines
medicines to lower blood pressure and treat heart problems (calcium channel blockers)
antidepressants
medicines to lower cholesterol, a type of fat in the blood (statins)
steroids
There are many herbal supplements that affect the CYP enzymes. These include:
St. John’s Wort
black cohosh
ginseng
gingko biloba
goldenseal
milk thistle
Tell your doctor or pharmacist if you are taking or considering taking herbal supplements. They can tell you if they might affect the CYP enzymes.
As well as your treatment for cancer, you may be taking medicines for other conditions. Taking multiple medicines means the pharmacist needs to check for any interactions that could happen between the medicines you are taking.
The interactions could be harmful and cause you side effects or your medicines may not work as well.
As well as the active ingredient, cancer drugs are also made up of other substances. These are called excipients. Excipients have several roles depending on the drug. These include:
improving taste (flavourings)
holding the ingredients together (binders)
improving their appearance (colourants)
making a medicine easy to handle (filler)
helping medicines to break apart in the body (disintegrants)
prolonging its shelf life (preservatives)
protecting the main drug until it is ready to be absorbed
Some excipients could cause problems if you have an allergy or are intolerant to them. You can check the excipients on the package information leaflet. Or you can ask the pharmacist.
Excipients include:
lactose - a milk sugar that’s made up of glucose and galactose
sorbitol – a sugar alcohol that is sugar free but has a sweet taste
sodium (salt) - you might need to take account of this if you are on a controlled sodium diet. Tell your doctor or pharmacist if you are on a low salt diet
arachis oil (peanut oil) - if you are allergic to peanut or soya, you should not take a medicine containing this
ethanol - a type of alcohol. Depending on the amount of alcohol you may need to avoid driving or operating machinery for a time after treatment. Your healthcare team will talk to you about this.
galactose – a milk sugar
glucose and sucrose are sugars - if you have you might need to check your blood sugars more often
sesame oil – if you are allergic to sesame seeds or sesame oil you should not take a medicine containing this
There are many reasons why people don’t take cancer drugs or other medicines in the way they’ve been told to. Some of these include:
not understanding exactly how or why to take them. Or that the instructions are too complicated
language barriers – having limited or no English
low reading ability or are unable to read
sight problems
forgetfulness – this could be due to a condition such as dementia
complicated medicine regimes
difficulty opening containers
difficulty swallowing
side effects - some people may stop taking a drug if they find the side effects difficult to cope with
There are things you can do to make sure you are taking your cancer drugs or other medicines as you should.
Find out:
why you are taking each drug. If you know what the drug is for and how important it is, it will help you to remember
how long you will be taking the drug for
what the side effects are for the drug and who you can contact if you have any problems
what to do if you miss a dose
If there is a language barrier there are:
interpreter services the healthcare professionals can use to help explain about the drug
labels they can print in different languages
If you have sight problems, you can ask for drug patient information sheets in large print, braille or as an audio CD. The pharmacist can order these through the electronic medicines compendium (EMC) website.
These can be helpful if you have several different drugs to take. They have compartments for each day of the week. There are smaller compartments for different times of the day.
Pillboxes are not suitable for cancer drugs such as chemotherapy tablets. This is because most need storing in their original container or they need to be handled in a special way.
Speak to your pharmacist first before using a pillbox.
Some things can help you remember to take your medicine on time. Most mobile phones have a health app that you can add your medicines to. You fill in the details, and it reminds you at the time they are due and how much (the dose).
Other ways include:
setting an alarm on your watch, clock, mobile phone or tablet
downloading a reminder app on your mobile phone or tablet
getting family to telephone or text you when the medicine is due
subscribing to a professional service that makes medicine calls or sends message reminders
in person visits to give or remind people to take medicines at the correct times
You could make a chart listing all your drugs and drug times if you’re taking more than one medicine daily. This can help you to remember if you have taken your medicines. You or your carer can tick off the medicines as you take them.
Your pharmacy can also create a chart. Speak to your pharmacist if you would like a chart listing all your drugs.
There are other ways to help remember to take medicines, but they might not be suitable if the medicine has to be stored in a certain way. Other ideas can include:
using sticky notes or notes and magnets to put in places that will remind you to take your drug
combining taking your drug with a regular daily activity like mealtimes (if you can have the drug with a meal)
putting the drug in the place where you visit or see often or by your task. For example, medicines you take in the morning being next to your toothbrush and those you take at night being on your bedside table
It is important to follow the instructions about how to take your cancer drugs and other medicines, and how you should store them.
Only you should handle the cancer drugs you are taking. You should wash your hands thoroughly after touching the drug. In some cases, you might need to wear gloves to take your cancer drug.
If you are unable to handle your cancer drugs, the person giving you them should not directly touch them. They should wear gloves. If the drug comes in a blister pack, they can push it out using the blister pack, so they don’t touch it. They should not give you your cancer drug unless absolutely necessary if they are:
pregnant or think they might be
breastfeeding
planning a pregnancy
Other important information
Check the expiration date of the drug before you take it.
Do not break or crush tablets or open capsules unless you have been told you can. Speak to your healthcare team if you have trouble with swallowing.
Get rid of any sharp objects, such as injections, in the sharps bin your nurse or pharmacist has given you. Keep this out of reach of children and pets.
Keep all medicines, including cancer drugs, away from children and pets as they can be very harmful. Keep them in a child and pet proof place.
Keep all medicines in their original packaging.
Store your medicine as directed by the pharmacist. This might be at room temperature or in the fridge. Some should be kept out of light.
Keep medicines away from heat, direct sunlight and moisture.
Many people keep medicines in the bathroom or kitchen cupboards. It is best to avoid storing medicines in these places as the temperature varies and the air may be damp.
Take any unused or out of date medicines back to the pharmacy. They can destroy them safely. Don't flush them down the toilet or throw them away in your dustbin.
Last reviewed: 12 Nov 2026
Next review due: 12 Nov 2029
You can have cancer drugs as an injection or drip through a vein, through a central line, PICC line or Portacath. Sometimes you might have it as an injection into a muscle or under the skin.
Cancer drugs have side effects and these can vary from person to person. But there are things that you can do to help you cope.
There are many different types of cancer drugs. Some treat cancer, and others help to relieve symptoms such as sickness and pain. The type of drugs you need for your cancer depends on what type of cancer you have.
Treatments can include surgery, radiotherapy and drug treatments (such as chemotherapy, hormone therapy or targeted cancer drugs). Find out about treatments and how to cope with side effects.
Find out about managing cancer symptoms and possible side effects from cancer treatment. There is information about pain, sickness, diet problems and much more.
