Cancer drugs A to Z list
Selinexor and dexamethasone is a cancer drug combination. You have:
selinexor (pronounced seh-lih-nek-sor)
dexamethasone (deks-ah-meth-uh-zone)
It is a treatment for myeloma.
You might have it when at least four other treatments have stopped working and the myeloma has come back (relapsed).
You might have these medicines as part of a .
Selinexor is a type of called a cancer growth blocker. It is known as a selective inhibitor of nuclear export (SINE).
It works by blocking the action of a within myeloma cells. The protein is called exportin 1 (XPO1). By blocking this protein it stops the myeloma cells growing and dividing, causing them to die.
Dexamethasone is a steroid. It helps selinexor to work better and to kill myeloma cells.
Find out more about targeted cancer drugs
Selinexor and dexamethasone are tablets.
You take selinexor with a glass of water. You need to swallow the tablets whole. Don’t break, crush or chew them. They can cause skin irritation when broken. You should take them at the same time every day. You can take selinexor with or without food.
You take dexamethasone after food or with milk as they can irritate your stomach. Taking them in the morning might help to stop difficulty in sleeping (insomnia).
Speak to your pharmacist if you have problems swallowing the tablets.
Whether you have a full or an empty stomach can affect how much of a drug gets into your bloodstream.
You should take the right dose, no more or less.
Talk to your healthcare team before you stop taking a cancer drug or if you miss a dose.
You have selinexor and dexamethasone as cycles of treatment. Each cycle of treatment lasts 28 days (4 weeks).
You take selinexor and dexamethasone twice a week. You take them in the morning on the same days each week. You have a 1 day gap between your dose.
So for example you take selinexor and dexamethasone on a Monday and Wednesday morning every week, with or just after breakfast.
You take them for as long as they are working and you are not experiencing too many side effects.
you take selinexor and dexamethasone on day 1 and day 3
you take selinexor and dexamethasone on day 8 and day 10
you take selinexor and dexamethasone on day 15 and day 17
you take selinexor and dexamethasone on day 22 and day 24
You then start the next cycle of treatment.
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).
Before each cycle of treatment you have a urine and blood test to check your levels.
Find out more about paraproteins for myeloma
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.
You might have medicines to try to prevent bacterial, viral or fungal infections.
These side effects happen in more than 10 in 100 people (more than 10%). You might have one or more of them. They include:
Feeling or being sick can be severe. You will have anti-sickness medicine to control the sickness. 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.
It might help to avoid fatty or fried foods, eat small meals and snacks and take regular sips of water.
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.
You might be breathless and look pale due to a drop in red blood cells. This is called anaemia.
Increased risk of getting an infection is due to a drop in white blood cells. 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 have medicines to try to prevent bacterial, viral or fungal infections
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.
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.
You might develop a cough or breathing problems. This could be due to infection, such as pneumonia or inflammation of the lungs.
You might have low levels of sodium or potassium in your blood. Less commonly, the levels of calcium, magnesium or phosphate might drop. Your levels of potassium and in your blood might go up.
You will have regular blood tests to check for this.
You or the people around you may notice that you feel confused.
Less commonly you might see things that aren’t there (hallucinations) or become really confused (delirious).
You might get extreme mood swings or feel very sad (depressed), but there isn’t enough information to work out how often these side effects might happen.
Tell your healthcare team straight away if you or the people around you notice any changes to your behaviour or personality.
You might have eye problems such as blurred vision. Other eye problems that can happen include clouding of the lens of the eye (cataracts) or being less able to see, but this is less common.
Let your healthcare team know straight away if you have any problems with your eyes.
High blood sugar levels can cause headaches, feeling thirsty and blurred vision. You have regular tests to check your blood sugar levels. You may need to check your levels more often if you have .
Dehydration means there isn't enough fluid in your body. You might find you aren't passing much urine and the colour is a very dark yellow. Your skin might be very dry and you might feel dizzy. So make sure you drink around 2 litres of fluid every day. Tell your nurse or doctor if you are not able to drink this much.
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.
Tell your healthcare team if you keep getting headaches. They can give you painkillers to help.
This drug might make you feel dizzy. Don’t drive or operate machinery if you have this.
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.
Less commonly you may have no taste. Let your healthcare team know of any taste changes.
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 laxative if needed.
Tell your doctor or nurse if you have this. They can check for the cause of the pain and give you medicine to help.
Tell your healthcare team straight away if you get a high temperature. Ask them if you can take paracetamol to help lower your temperature.
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.
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:
sepsis - a serious reaction to an infection. signs can include feeling very unwell, not passing urine, being sick, a very high or very low temperature or shivering. Contact your advice line straight away if you have any of these symptoms
problems with your pancreas. You will have regular blood tests to check how your pancreas is working
fainting
faster heartbeat or pulse
problems with your balance
memory problems - including problems remembering recent events
low blood pressure (hypotension), tell your doctor or nurse if you feel lightheaded or dizzy
feeling like the room is spinning (vertigo)
indigestion, symptoms include heartburn, bloating and burping
dry mouth
farting or bloating
itchy skin
muscle spasms
problems with your kidneys. You will have regular blood tests to check your kidneys
liver changes - you have regular blood tests to check for any changes in the way your liver is working
falls
chills
hair loss
night sweats and an increase in sweating
feeling generally unwell
These side effects happen in fewer than 1 in 100 people (less than 1%). You might have one or more of them. They include:
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
inflammation in the brain – causing confusion, headaches and fits (seizures)
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:
weight gain
a build up of fluid causing swelling in your face, arms, legs or other parts of your body
high levels of a fatty substance called cholesterol in your blood
thinner and weaker bones that are fragile and more likely to break (osteoporosis)
thinning of the skin
slower wound healing
high blood pressure, tell your doctor or nurse if you have headaches, nosebleeds, blurred or double vision or shortness of breath
blood clots that can be life threatening; signs are pain, redness and swelling where the clot is. Feeling breathless can be a sign of a blood clot in the lung. Contact your advice line or doctor straight away if you have any of these symptoms
dexamethasone can cause severe heart problems if you have had a recent heart attack
You might have other side effects that aren't listed on this page. Look at the individual drug page for dexamethasone.
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 treatment might harm a baby developing in the womb. It is important not to become pregnant or get someone pregnant while you're having treatment and for at least a week afterwards.
Talk to your doctor or nurse about effective contraception before starting treatment. Let them know straight away if you or your partner become pregnant.
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.
Don’t breastfeed during this treatment and for 1 week after your last dose, because it is not known if the drug could come through into your breast milk.
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: 25 Oct 2025
Next review due: 25 Oct 2029
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