Ruxolitinib (Jakavi®)

Ruxolitinib (Jakavi®) is a targeted therapy drug. It is used to treat some types of myeloproliferative neoplasms (MPNs).

What is ruxolitinib (Jakavi®)?

Ruxolitinib (Jakavi®) is used to treat some types of myeloproliferative neoplasms (MPNs). MPNs are types of cancer that affect how blood cells are made. They happen when the bone marrow makes:

  • too many of one type of blood cell
  • more than one type of blood cell.

Ruxolitinib is used to treat myelofibrosis and polycythaemia vera. It is best to read this information with our information about blood cancer.

Ruxolitinib belongs to a group of targeted therapy drugs known as protein kinase inhibitors. It targets genes called JAK1 and JAK2. These genes help control the number of blood cells made. If either gene becomes faulty, the body may make too many blood cells. Ruxolitinib blocks (inhibits) signals from the faulty gene. This reduces the number of extra blood cells made.

Ruxolitinib can also block other signals that cause too many blood cells to be made. It can also work for people who do not have a faulty JAK gene.

Your doctor will talk to you about this treatment and its possible side effects before you agree (consent) to have treatment.

How ruxolitinib is given

You will be given ruxolitinib as tablets that you take at home.

During treatment you usually see a blood cancer doctor (haematologist), a specialist nurse, and a specialist pharmacist. This is who we mean when we mention doctor, nurse or pharmacist in this information.

You will have regular blood samples taken throughout your treatment. These allow your doctor to check:

  • the levels of different blood cells (blood count) in your body
  • how your liver and kidneys are working
  • how well the treatment is working.

Your course of ruxolitinib

The nurse or pharmacist will give you the ruxolitinib tablets to take home. Always take them exactly as explained. This is important to make sure they work as well as possible for you.

Your nurse or pharmacist may also give you other drugs to take home. Take all your drugs and medicines exactly as they have been explained to you.

Your doctor may need to change the dose of ruxolitinib throughout your treatment. This depends on the results of your blood tests.

You will usually continue taking ruxolitinib for as long as it is working well for you. It is important that you do not stop taking it without talking to your doctor first. Stopping the drug suddenly may make you feel unwell. Doctors usually reduce your dose before stopping it completely.

Taking ruxolitinib tablets

Take the tablets with or without food. Swallow the tablets whole with a glass of water. Speak to your doctor or pharmacist if you find this difficult. Do not chew, open or crush your tablets.

If you forget to take your ruxolitinib, do not take a double dose. Keep to your regular schedule and take your next dose at the right time.

Other things to remember about your tablets include the following:

  • Do not eat grapefruit or drink grapefruit juice or Seville oranges while you are taking ruxolitinib. These can affect how the drug works.
  • Keep the tablets in their original package, at room temperature, and away from heat and direct sunlight.
  • Keep the tablets safe and out of sight and reach of children.
  • If you are sick just after taking the tablets, contact the hospital. Do not take another dose.
  • If your treatment is stopped return any unused tablets to the pharmacist.

About side effects

We explain the most common side effects of this treatment here. We also include some less common side effects.

You may get some of the side effects we mention, but you are unlikely to get all of them. If you are also having treatment with other cancer drugs, you may have some side effects that we have not listed here. Always tell your doctor, nurse or pharmacist about any side effects you have.

Your doctor can give you drugs to help control some side effects. It is important to take them exactly as your nurse or pharmacist explains. This means they will be more likely to work for you. Your nurse will give you advice about managing your side effects. After your treatment is over, most side effects start to improve.

Serious and life-threatening side effects

Some cancer treatments can cause severe side effects. Rarely, these may be life-threatening. Your cancer doctor or nurse can explain the risk of these side effects to you.

Contact the hospital

Your nurse will give you telephone numbers for the hospital. If you feel unwell or need advice, you can call them at any time of the day or night. Save these numbers in your phone or keep them somewhere safe.

More information

We cannot list every side effect for this treatment. There are some rare side effects that are not listed. You can visit the electronic Medicines Compendium (eMC) for more detailed information.

Possible side effects

Risk of infection

This treatment can reduce the number of white blood cells in your blood. These cells fight infection. If the number of white blood cells is low, you are more likely to get an infection. A low white blood cell count is sometimes called neutropenia.

An infection can be very serious when the number of white blood cells is low. It is important to get any infection treated as soon as possible. Contact the hospital straight away on the 24-hour contact number you have been given if:

  • your temperature goes over 37.5°C (99.5°F)
  • you suddenly feel unwell, even with a normal temperature
  • you have symptoms of an infection
  • your temperature goes below 36°C (96.8°F).

Symptoms of an infection include:

  • feeling shivery and shaking
  • a sore throat
  • a cough
  • breathlessness
  • diarrhoea
  • needing to pass urine (pee) a lot, or discomfort when you pass urine.

It is important to follow any specific advice your cancer treatment team gives you.

You will have regular blood tests during treatment. If needed, your doctor may reduce or delay your treatment for a short time, until your cell count increases.


Some people can get shingles (herpes zoster) while taking ruxolitinib. This is an infection of a nerve and the skin around it. It is caused by the same virus that causes chickenpox.

Tell your doctor straight away if you develop any of the following on your skin:

  • a burning feeling
  • tingling
  • numbness
  • itchiness
  • a rash with blisters.

Bruising and bleeding

This treatment can reduce the number of platelets in your blood. Platelets are cells that help the blood to clot. Tell your doctor if you have any bruising or bleeding that you cannot explain. This includes:

  • nosebleeds
  • bleeding gums
  • tiny red or purple spots on the skin that may look like a rash.

Some people may need a drip to give them extra platelets. This is called a platelet transfusion.

Ruxolitinib can sometimes cause more serious bleeding. Contact the hospital straight away on the contact number you have been given if you:

  • pass black or bloodstained stools (poos)
  • vomit blood
  • vomit and it looks like coffee grounds.

Anaemia (low number of red blood cells)

This treatment can reduce the number of red blood cells in your blood. Red blood cells carry oxygen around the body. If the number of red blood cells is low, this is called anaemia. You may have symptoms such as:

  • pale skin
  • lack of energy
  • feeling breathless
  • feeling dizzy and light-headed.

Tell your doctor or nurse if you have these symptoms.

If you are very anaemic, you may need a drip to give you extra red blood cells. This is called a blood transfusion.


This treatment can cause dizziness. Tell your doctor or nurse if this happens. Do not drive or operate machinery if you feel dizzy.

Increased cholesterol levels

The drug can increase the cholesterol level in your blood. Your doctor will monitor this with blood tests.

Excess wind

Some people pass more wind than usual when taking ruxolitinib. If you are affected, try to avoid food that gives you wind, for example:

  • beans
  • pickles
  • fizzy drinks.


This treatment can cause constipation. Constipation means that you are not able to pass stools (poo) as often as you normally do. It can become difficult or painful. Here are some tips that may help:

  • Drink at least 2 litres (3½ pints) of fluids each day.
  • Eat high-fibre foods, such as fruit, vegetables and wholemeal bread.
  • Do regular gentle exercise, like going for short walks.

If you have constipation, contact the hospital for advice. Your doctor can give you drugs called laxatives to help.

Changes in the way your liver works

Ruxolitinib can affect how your liver works. You will have regular blood tests during treatment to check how well your liver is working. Some people may be given a lower dose of ruxolitinib if they have or have had liver problems.

Weight gain

Ruxolitinib may cause weight gain. Talk to your doctor if this happens.


This treatment may cause headaches. If you have headaches, tell your doctor. They may give you painkillers to help.

Increased blood pressure

Ruxolitinib can cause high blood pressure. Your blood pressure will be checked regularly. Tell your doctor if you already have high blood pressure and are on treatment to control it.

Less common side effects

Risk of developing skin cancer (non-melanoma)

A small number of people taking ruxolitinib develop skin cancer. Doctors are not sure if this is directly linked to the drug. There may be other reasons. Your doctor will discuss the risk of developing skin cancer with you. Tell your doctor if you notice any changes in your skin. They may recommend taking extra care in the sun.

Effects on the nervous system

This drug may cause a bleed, or rarely, a serious infection in the brain. Contact the hospital straight away if you, or someone else, notices you:

  • are confused or drowsy
  • have slurred speech
  • have changes in your vision
  • have difficulty with your balance or walking
  • have weakness on one side of your body.

Other information

Blood clot risk

Cancer and some cancer treatments can increase the risk of a blood clot. Symptoms of a blood clot include:

  • throbbing pain, redness or swelling in a leg or arm
  • suddenly feeling breathless or coughing
  • sharp chest pain, which may be worse when you cough or take a deep breath.

If you have any of these symptoms, contact the hospital straight away on the 24-hour contact number you have been given. If you cannot get through to your doctor, call the NHS urgent advice number on 111.

A blood clot is serious, but it can be treated with drugs that thin the blood (anticoagulants). Your doctor or nurse can give you more information.

You can help reduce the risk of developing a blood clot by:

  • staying active during treatment
  • drinking plenty of fluids, especially water.

You may be given anticoagulants to help prevent a clot.

Other medicines

Some medicines can affect how this treatment works or be harmful when you are having it. Always tell your cancer doctor about any drugs you are taking or planning to take, such as:

  • medicines you have been prescribed
  • medicines you buy in a shop or chemist
  • vitamins, herbal drugs and complementary therapies.

Tell other doctors, pharmacists or dentists who prescribe or give you medicines that you are having this cancer treatment.

You can visit the electronic Medicines Compendium (eMC) for more detailed information about your treatment.


Ruxolitinib contains a sugar called lactose. You should not take it if you have a lactose intolerance. Ask your doctor, nurse or pharmacist if you need more information.


Vaccinations can reduce your risk of getting certain infections. Your doctor or nurse may talk to you about having vaccinations.

Doctors usually recommend that people with cancer have a flu vaccination and a coronavirus vaccination. These are both inactivated vaccinations that can help reduce the risk of infection. People with weak immune systems can have these, as they are not live vaccinations.

If your immune system is weak, you need to avoid live vaccinations. This is because they can make you unwell. Live vaccines, such as shingles, contain a very weak version of the illness they are vaccinating you against. Your cancer doctor or GP can tell you more about live and inactivated vaccinations.

Hepatitis reactivation

Tell your doctor if you have had Hepatitis B or C (a liver infection) in the past. This treatment can make it active again. Your doctor or nurse will talk to you about this and may test you for it.

Tuberculosis (TB)

Tell your doctor if you have had tuberculosis (TB) in the past. This treatment can make it active again. You should also tell your doctor if you been in close contact with someone who has TB.


Your doctor will advise you not to get pregnant or make someone pregnant while having this treatment. The drugs may harm a developing baby. It is important to use contraception during your treatment and for a while after treatment finishes. Your doctor, nurse or pharmacist can tell you more about this.


You are advised not to breastfeed while having this treatment, or for some time after treatment finishes. This is because the drugs could be passed to the baby through breast milk.

Your doctor or nurse can give you more information.


Some cancer drugs can affect whether you can get pregnant or make someone pregnant. If you are worried about this, it is important to talk with your doctor before you start treatment.

Medical and dental treatment

If you need medical treatment for any reason other than cancer, always tell the doctors and nurses you are having cancer treatment. Give them the contact details for your cancer doctor so they can ask for advice.

If you think you need dental treatment, talk to your cancer doctor or nurse. Always tell your dentist you are having cancer treatment.