Cancer drugs A to Z list
Trastuzumab and pertuzumab are types of targeted cancer drugs. It is a treatment for breast cancer.
You pronounce trastuzumab as tras-too-zoo-mab and pertuzumab as per-too-zoo-mab.
You can only have this medicine if your breast cancer is positive. You have tests on your breast cancer cells to check this.
You might have trastuzumab and pertuzumab with other drugs.
Trastuzumab and pertuzumab also comes as a combined injection called Phesgo. This page is about having trastuzumab and pertuzumab as a drip into your bloodstream.
Go to information about Phesgo
Trastuzumab and pertuzumab are types of targeted cancer drugs called monoclonal antibodies. Monoclonal antibodies work by attaching to proteins on the surface of the cancer cells.
Human epidermal growth factor 2 (HER2) is a protein that makes cells grow and divide. Some cancers have large amounts of HER2 protein. They are called HER2 positive cancers.
Trastuzumab and pertuzumab work by locking onto HER2 on the cancer cells. The aim is to stop the cells from growing and kill them. They only work if your cancer is HER2 positive.
Find out more about monclonal antibodies and how they work
You have pertuzumab into your bloodstream (intravenously). You have trastuzumab either intravenously or as an injection under the skin (subcutaneously).
If you are having trastuzumab as an injection, your doctor or nurse gives you this injection into your thigh. For each dose you have the injection in the opposite thigh. For example, you have one dose in your right thigh and the next in your left. You have the injection in a new place on your thigh at each injection.
You might have trastuzumab and pertuzumab through a long plastic tube that goes into a large vein in your chest. The tube stays in place throughout the course of treatment. This can be a
central line
PICC line
portacath
You might have treatment through a thin short tube (a cannula) that goes into a vein in your arm. You have a new cannula each time you have treatment.
You have trastuzumab and pertuzumab as cycles of treatment. This means that you have the drugs and then a rest to allow your body to recover. You have it once every 3 weeks (21 days).
There are several different ways of having this treatment. Exactly how you have the cancer drugs depends on your situation. Your doctor, nurse or pharmacist will tell you more about your treatment plan before you start.
You usually have trastuzumab as a drip into your bloodstream over 90 minutes. You usually have pertuzumab over 60 minutes. These times may change after you have had your first dose, but this depends if you had any side effects when the treatment was going in.
You have blood tests before and during your treatment. They check your levels of and other substances in the blood. They also check how well your liver and kidneys are working.
Before treatment starts you may have a blood test to check for viruses such as hepatitis B, hepatitis C, and HIV. This is called a viral screen.
It’s important for your doctor to know if you have had any of these viruses. This is because this treatment can weaken your and can cause the virus to become active again (reactivation).
Trastuzumab and pertuzumab can affect how well your heart works. You usually have tests such as an before you start your treatment and at different times throughout.
Find out about these tests in our A-Z list
Side effects can vary from person to person. They also depend on what other treatments you're having.
Your doctor, nurse or pharmacist will go through the possible side effects. They will monitor you during treatment and check how you are at your appointments. Contact your advice line as soon as possible if:
you have severe side effects
your side effects aren’t getting any better
your side effects are getting worse
Early treatment can help manage side effects better.
We haven't listed all the side effects here. Talk to your healthcare team if you have any new symptoms that you think might be a side effect of your treatment.
Remember it is very unlikely that you will have all of these side effects. But you might have some of them at the same time.
These side effects happen in more than 10 in 100 people (more than 10%). You might have one or more of them. They include:
Increased risk of getting an infection is due to a drop in . Symptoms include a change in temperature, aching muscles, cough, headaches, feeling cold and shivery, pain or a burning feeling when peeing or generally feeling unwell. You might have other symptoms depending on where the infection is.
Infections can sometimes be life threatening. You should contact your advice line urgently if you think you have an infection.
You might be breathless and look pale due to a drop in . This is called anaemia.
This is due to a drop in the number of platelets in your blood. These blood cells help the blood to clot when we cut ourselves. You may have nosebleeds or bleeding gums after brushing your teeth. Or you may have lots of tiny red spots or bruises on your arms or legs. This is known as petechiae.
A reaction may happen during the infusion. Symptoms can include a skin rash, itching, swelling of the lips, face or throat, breathing difficulties, fever and chills. Your nurse will give you medicines beforehand to try to prevent a reaction. Allergic reactions can sometimes be life threatening.
You might have heart problems such as a change in your heart rhythm or it may feel like a flutter. There might be a change to the measurement of how well your heart pumps blood around the body properly.
Less commonly the muscle of your heart can get weak, stiff, thicken and swell.
You might also get fluid around the heart (pericardial effusion), but this is rare.
Let your healthcare team know if you have any symptoms such as a faster heartbeat, shortness of breath, feeling tired, dizzy or lightheaded, chest pain or swollen ankles and legs.
Your blood pressure may be lower or higher than normal. Tell your nurse if you feel dizzy, faint, or if you have headaches, nosebleeds, blurred or double vision, or shortness of breath.
Your blood pressure usually goes back to normal while you are on treatment or when treatment ends.
You might feel very tired and as though you lack energy.
Various things can help you to reduce tiredness and cope with it, for example exercise. Some research has shown that taking gentle exercise can give you more energy. It is important to balance exercise with resting.
Contact your advice line if you have diarrhoea. For example, in one day you have 2 or more loose bowel movements than usual. If you have a , you might have more output than normal. Your doctor may give you anti diarrhoea medicine to take home with you after treatment.
Try to eat small meals and snacks regularly. It’s best to try to have a healthy balanced diet if you can. You don’t necessarily need to stop eating foods that contain . But if your diet is normally very high in fibre, it might help to cut back on high fibre foods such as beans, nuts, seeds, dried fruit, bran and raw vegetables.
Drink plenty to try and replace the fluid lost. Aim for 8 to 10 glasses per day.
Feeling or being sick is usually well controlled with anti sickness medicines. It might help to avoid fatty or fried foods, eat small meals and snacks and take regular sips of water. Relaxation techniques might also help.
It is important to take anti sickness medicines as prescribed even if you don’t feel sick. It is easier to prevent sickness rather than treat it once it has started.
You might have pain in different areas of your body including your muscles, joints, chest, arms, legs and tummy (abdomen).
Other less common sites of pain include your bones, back, neck, or you might have arthritis. Tell your doctor or nurse about any pain you are having, they can work out the cause and give you medicines to help.
Skin problems include a skin rash, dry, itching and reddening. The skin on your hands and feet may become sore, red, or may peel. You may also have tingling, numbness, pain and dryness. This is called hand-foot syndrome or palmar plantar syndrome.
Occasionally you might have general inflammation of the skin (dermatitis). Red pimples or bumps on the face (acne) can also be a side effect.
Rarely, you might have raised red or skin colour patches on your skin. They might be itchy, burn or sting. This is a skin reaction. The rash might be harder to see on black or brown skin.
Your nails may become brittle, dry, change colour or develop ridges. Less commonly this treatment can cause your nail to separate from the nail bed.
You might not feel like eating and may lose weight. Eating several small meals and snacks throughout the day can be easier to manage. You can talk to a dietitian if you are concerned about your appetite or weight loss.
Mouth sores and ulcers can be painful. It helps to keep your mouth and teeth clean, drink plenty of fluids and avoid acidic foods such as lemons. Chewing gum can help to keep your mouth moist. Tell your doctor or nurse if you have ulcers.
Less commonly your mouth might be dry.
is easier to sort out if you treat it early. Drink plenty and eat as much fresh fruit and vegetables as you can. Try to take gentle exercise, such as walking. Tell your healthcare team if you think you are constipated. They can give you a if needed.
If you have difficulty sleeping, it can help to change a few things about how you try to sleep. Try to go to bed and get up at the same time each day and spend some time relaxing before you go to bed. Some light exercise each day may also help.
Contact your doctor or pharmacist if you have indigestion or heartburn. They can prescribe medicines to help.
Taste changes may make you go off certain foods and drinks. You may also find that some foods taste different from usual or that you prefer to eat spicier foods. Your taste gradually returns to normal a few weeks after your treatment finishes.
A build up of fluid may cause swelling in your arms, hands, ankles, and legs. Less commonly you might have a build up of fluid in other parts of the body. Contact your healthcare team if this happens to you.
You could lose all your hair. This includes your eyelashes, eyebrows, underarms, legs and sometimes pubic hair. Your hair will usually grow back once treatment has finished but it is likely to be softer. It may grow back a different colour or be curlier than before.
You may have headaches, muscle aches (myalgia), a high temperature, sore throat, blocked or runny nose, loss of taste or smell and shivering. You should contact your advice line urgently if you have these symptoms.
Numbness or tingling in fingers or toes is often temporary and can improve after you finish treatment. Tell your healthcare team if you're finding it difficult to walk or complete fiddly tasks such as doing up buttons.
Other nerve changes may include an unpleasant feeling when being touched, loss of feeling or nerve pain. Nerve pain can feel like something is burning, stabbing, prickling or like an electric shock.
You might have eye problems including watery eyes or blurred vision, sore, red, itchy and dry eyes (conjunctivitis).
Tell your healthcare team if you have any of these symptoms, they might be able to give you medicines to help.
Tell your healthcare team if you keep getting headaches. They can give you painkillers to help.
This treatment might make you feel dizzy. Don’t drive or operate machinery if you have this.
We have some tips for coping with hot flushes in women and hot flushes in men. This information also includes some of the possible treatments. Talk to your doctor if your hot flushes are hard to cope with. They might be able to prescribe some medicines to help.
This treatment may cause of the . You might have soreness or pain in your throat, food pipe, abdomen and back passage (rectum).
Symptoms depend on where the inflammation is but it can include mouth ulcers, difficulty swallowing, feeling or being sick, diarrhoea with or without blood and pain.
Let your doctor, nurse or pharmacist know if you have this.
You may develop shaky hands also known as a tremor with this treatment.
This treatment can cause lung problems including shortness of breath and a cough.
Less commonly this treatment can cause an infection, a build up of fluid in the lungs. Or inflammation and narrowing of the air ways (asthma).
Rarely, you can develop a wheeze, inflammation, stiffness or scarring of the lung tissue.
Symptoms of breathing problems include shortness of breath, chest pain, a cough, changes or difficulty breathing, wheezing, chest tightness, and feeling very tired.
You might get a high temperature. Or you might feel cold or start shivering (chills).
These side effects happen in between 1 and 10 out of every 100 people (between 1 and 10%). You might have one or more of them. They include:
feeling anxious, or very low in mood (depressed)
feeling very sleepy or difficult to wake up (somnolence)
swollen veins near your anus (piles or haemorrhoids). This can be painful when you have a poo - let your team know if you have this
changes to the way your kidneys work - you have regular blood tests to check this
feeling generally unwell
swollen or sore breasts
liver changes – symptoms can include feeling very tired, feeling or being sick, loss of appetite, tummy pain, yellowing of the skin or whites of the eyes (jaundice) or itchy skin
widening of your blood vessels that can make you feel weak, lightheaded, dizzy, faint and confused
sweating more than usual
muscle tightening, spasms and not able for them to relax, this can cause stiffness and making things like your legs difficult to move (hypertonia)
These side effects happen in fewer than 1 in 100 people (less than 1%). You might have one or more of them. They include:
hearing loss
high levels of chemicals in your blood due to the breakdown of tumour cells (tumour lysis syndrome) - you have regular blood tests to check for this
- symptoms include high temperature, chills, headache, difficulty breathing and dizziness
There isn't enough information to work out how often these side effects might happen. You might have one or more of them. They include:
your blood taking longer to stop bleeding or clot due to the liver not making enough vitamin K
low levels of potassium in the blood
We have more information about side effects and tips on how to cope with them.
Cancer drugs can interact with medicines, herbal products, and some food and drinks. We are unable to list all the possible interactions that may happen. An example is grapefruit or grapefruit juice which can increase the side effects of certain drugs.
Tell your healthcare team about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies. Also let them know about any other medical conditions or allergies you may have.
This drug may harm a baby developing in the womb. It is important not to become pregnant while you are having this treatment and for at least 7 months afterwards.
Talk to your doctor or nurse about effective contraception before starting treatment. Let them know straight away if you become pregnant while having treatment.
It is not known whether this treatment affects in people. Talk to your doctor before starting treatment if you think you may want to have a baby in the future.
It is not known whether these drugs come through into breast milk. Doctors usually advise that you don’t breastfeed during this treatment and for 7 afterwards.
If you are having tests or treatment for anything else, always mention your cancer treatment. For example, if you are visiting your dentist.
Don’t have immunisations with live vaccines while you’re having treatment and for up to 12 months afterwards. The length of time depends on the treatment you are having.
Ask your doctor or pharmacist how long you should avoid live vaccinations.
In the UK, live vaccines include rubella, mumps, measles, BCG, and yellow fever.
You can usually have:
other vaccines, but they might not give you as much protection as usual
the flu vaccine (as an injection)
the coronavirus (COVID-19) vaccine
Talk to your doctor or pharmacist about the best time to have a vaccine in relation to your cancer treatment.
You can be in contact with other people who have had live vaccines as injections. If someone has had a live vaccine by mouth or nasal spray there may be a small risk the vaccine virus can be passed onto you if your is weakened.
Your healthcare team will let you know if you need to take any precautions if you are in close contact with someone who has had a live vaccine.
For further information about each drug and the possible side effects go to the electronic Medicines Compendium (eMC) website. You can find patient information leaflets for each drug on this website.
You can report any side effect you have to the Medicines and Healthcare Regulatory Agency (MHRA) as part of their Yellow Card Scheme.
Last reviewed: 01 Jul 2026
Next review due: 01 Jul 2029
Find out about breast cancer, including symptoms, diagnosis, treatment, survival, and how to cope with the effects on your life and relationships.
Secondary breast cancer means that a cancer that began in the breast has spread to another part of the body such as the bones or lungs.
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.
Targeted cancer drugs work by ‘targeting’ the differences that help a cancer cell to survive and grow. They are one of the main treatments for some cancers.
Coping with cancer can be difficult. There is help and support available. Find out about the emotional, physical and practical effects of cancer and how to manage them.
About Cancer generously supported by Dangoor Education since 2010. Learn more about Dangoor Education
Search our clinical trials database for all cancer trials and studies recruiting in the UK.
Connect with other people affected by cancer and share your experiences.
Questions about cancer? Call freephone 0808 800 40 40 from 9 to 5 - Monday to Friday. Alternatively, you can email us.
