Trametinib (Mekinist)

How does trametinib work?

Trametinib is a type of targeted cancer drug called a cancer growth blocker. It works by targeting certain proteins that help cancer cells grow. By blocking these proteins, it stops or slows down the growth of cancer cells.

Learn more about cancer growth blockers

How do you take trametinib?

You take trametinib as a tablet.

You swallow it with a full glass of water and do not crush or chew it. You take it on an empty stomach. This means you take it at least 1 hour before a meal or 2 hours after a meal.

Whether you have a full or empty stomach can affect how much of a drug gets into your bloodstream.

You should take the right dose, not more or less.

Talk to your healthcare team before you stop taking a cancer drug, or if you have missed a dose.

How often do you take trametinib?

You take trametinib once a day at the same time each day.

You continue treatment for as long as it is working and you aren’t experiencing too many side effects.

Tests

You have blood tests before and during your treatment. They check your levels of blood cells 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 immune system and can cause the virus to become active again (reactivation).

You also have tests such as an ECHO or ECG to check your heart before and during your treatment.

Find out more about tests and scans

What are the side effects of trametinib?

Side effects can vary from person to person. They also depend on what other treatments you're having.

When to contact your team

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.

Common side effects

These side effects happen in more than 10 in 100 people (more than 10%). You might have one or more of them. They include:

High blood pressure (hypertension)

Tell your doctor or nurse if you have headaches, nosebleeds, blurred or double vision or shortness of breath. You have your blood pressure checked regularly.

Bleeding

This drug can cause bleeding from anywhere in your body. This is usually mild but there is a risk of a serious bleed. Signs of bleeding include blood in your pee or poo, black poo, vomiting or coughing up blood, headaches, dizziness or feeling weak.

High temperature (fever)

Tell your healthcare team straightaway if you get a high temperature. This drug can affect your body’s ability to control temperature. Having a fever doesn’t always mean you have an infection. But you should call your advice line, as an infection can be serious if not treated quickly.

Cough or shortness of breath

Tell your doctor or nurse if you develop a cough or feel short of breath. Rarely, this could be due to inflammation of the lungs (pneumonitis).

Diarrhoea or constipation

Tell your healthcare team if you have diarrhoea or constipation. They can give you medicine to help.

Feeling or being sick

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.

Tummy (abdominal) pain

Tell your doctor or nurse if you have this. They can check for the cause of the pain and give you medicine to help.

Dry mouth

A dry mouth is also called xerostomia (pronounced zero-stow-mee-a). Talk to your healthcare team for advice if you have this. It can help to drink plenty of fluids.

Skin problems

Symptoms of skin problems can include a rash, dry skin and itching and raised red bumps that are usually filled with pus and may have a crust.

Less commonly this medicine can cause redness or make the skin split or cracked. 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.

Let your healthcare team know if you notice any changes to your skin.

Hair loss

Your hair may thin but you’re unlikely to lose all your hair. This usually starts after your first or second cycle of treatment. It is almost always temporary and your hair will grow back when you finish your treatment.

Tiredness and weakness

Tiredness and weakness (fatigue) can happen during and after treatment. Doing gentle exercises each day can keep your energy up. Don't push yourself, rest when you start to feel tired and ask others for help.

Talk to your doctor or nurse if this effect is stopping you from doing your usual daily activities.

Fluid build up

A build up of fluid may cause swelling in your arms, hands, ankles, legs, face and other parts of the body. Contact your healthcare team if this happens to you.

Liver changes

You might have liver changes that are usually mild and unlikely to cause symptoms. They usually go back to normal when treatment finishes.

You have regular blood tests to check for any changes in the way your liver is working.

Occasional side effects

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:

• an allergic reaction that can cause a rash, shortness of breath, redness or swelling of the face and dizziness - some allergic reactions can be life threatening. Alert your nurse if you notice any of these symptoms

• low levels of red blood cells in your blood - this is called anaemia. This can make you feel weak and tired

• infection such as deep skin infection (cellulitis) or inflammation of the hair follicles (folliculitis)

• loss of fluid in the body (dehydration) – signs include feeling dizzy, you may not pee much and it might be dark in colour

• eye problems such as blurred vision or swelling around the eyes. More rarely you might have, eye pain, flashes of light, floaters (tiny spots that appear in your vision) and redness in your eyes. You might have an eye test before you start treatment

• heart problems including a drop in how well the heart pumps blood or how fast your heart beats (rate). Very rarely, your heart might stop working properly

• sore mouth and ulcers

• numbness or tingling in fingers or toes (peripheral neuropathy) - this is often temporary and can improve after you finish treatment. Let your healthcare team know if you’re finding it difficult to walk or complete fiddly tasks such as doing up buttons

• inflammation of tissue lining (mucosa). The mucosa lines a number of different areas in the body such as your mouth, bowel and airways

• a build up of lymph fluid that causes swelling in a part of the body (lymphoedema)

• a high level of an enzyme in your blood that can be a sign of injury to muscle, including the heart

Rare side effects

These side effects happen in fewer than 1 in 100 people (fewer than 1%). You might have one or more of them. They include:

• a condition that causes your muscles to breakdown (rhabdomyolysis) -this can be serious if not treated quickly. Symptoms include muscle pain or weakness, dark urine, tiredness, dehydration and confusion

• inflammation of the bowel (colon) causing tummy pain, diarrhoea, fever, blood in your poo

Coping with side effects

We have more information about side effects and tips on how to cope with them.

Read more about how to cope with side effects

What else do you need to know?

Other medicines, foods and drink

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.

Loss of fertility

You may not be able to become pregnant after treatment with this drug. Talk to your doctor before starting treatment if you think you may want to have a baby in the future.

You might be able to store eggs or ovarian tissue. But this service is not available in every hospital, so you would need to ask your doctor about this.

Pregnancy and contraception

This treatment may harm a baby developing in the womb. It is important not to become pregnant while you are having treatment and for 16 weeks 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.

Breastfeeding

It is not known whether this drug comes through into the breast milk. Doctors usually advise that you don’t breastfeed during this treatment.

Treatment for other conditions

If you are having tests or treatment for anything else, always mention your cancer treatment. For example, if you are visiting your dentist.

Immunisations

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.

Contact with others who have had immunisations

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 immune system 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.

Read more about immunisations and cancer treatment

More information about this treatment

For further information about this treatment and possible side effects go to the electronic Medicines Compendium (eMC) website. You can find the patient information leaflet on this website.

eMC website

You can report any side effect you have to the Medicines Health and Regulatory Authority (MHRA) as part of their Yellow Card Scheme.

Report a side effect to the MHRA