Cancer drugs A to Z list
Triptorelin is a type of . You pronounce it as trip-toe-reh-lin.
It is a treatment for prostate cancer.
Triptorelin is also used to treat breast cancer.
Prostate cancer depends on to grow. Testosterone is a type of that your body naturally produces. Triptorelin blocks messages from the brain that normally tell the body to make testosterone. By blocking these messages, triptorelin reduces the amount of testosterone in the body. This can slow down or stop the growth of the cancer.
Find out more about how hormone therapy works
You usually have triptorelin as an injection into a muscle (intramuscular), in your buttock or upper thigh.
If you're having a type called Gonapeptyl Depot, you can have the injection under the skin (subcutaneous injection) into your tummy (abdomen), thigh or top of your arm. You might have stinging or a dull ache for a short time after this type of injection, but they don't usually hurt much. The skin in the area may go red and itchy for a while.
You might have it triptorelin:
once a month
every 3 months
every 6 months
You continue taking triptorelin for as long as the treatment is working and you are not experiencing too many side effects.
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.
Side effects can vary from person to person. They also depend on what other treatment you are having.
Your doctor, nurse, or pharmacist will go through the possible side effects. They will monitor you closely 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
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 a temporary worsening of your symptoms after your first injection. They usually stop after 1 or 2 weeks. This is called tumour flare. So your doctor might give you another type of hormone drug to take at the same time to prevent the symptoms of tumour flare.
Symptoms of tumour flare include:
increased pain or difficulty passing urine
bone pain
back pain
blood in your urine
These side effects happen in more than 10 in 100 people (more than 10%). You might have one or more of them. They include:
Low testosterone levels can lower your interest in sex.
It can help to talk this through with your partner. You can still feel close to each other through cuddling and kissing. It may also help to talk to a counsellor or therapist. Your doctor or nurse can organise this for you.
You may have hot flushes and sweat a lot. We have some tips for coping with 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.
It is common to have back pain, joint pain or bone pain. Occasionally, you may get hand or foot pain, muscle aches, muscle pain and joint stiffness. Rarely you might have upper tummy (abdominal) pain or pain in the breasts or testicles. Let your healthcare team know so they can advise you on how to help reduce it.
You might feeling pain or discomfort when peeing (passing urine). You might need to get up in the night to pee.
You might have problems getting an erection (impotence). Talk to your doctor or nurse if you have this. There are treatments that can help, such as medicines, vacuum pumps and injections or pellets. Your doctor or nurse can refer you to a specialist in this area.
You might have unusual skin sensations such as numbness, tingling, prickling or burning in your legs. It can feel like pins and needles.
Let your doctor or nurse know if you have this.
You might feel weak and as though you lack energy. Various things can help you to 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.
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 or doctor if notice any of these symptoms
a change in mood or
dizziness
headaches
high blood pressure
dry mouth
feeling sick
redness, inflammation or tenderness at the injection site
swelling due to a fluid build up in different parts of the body (oedema)
pain in different parts of your body such as the , hands or feet. Or aches and pain in the muscles, bones, joints, ligaments, tendons or nerves (musculoskeletal system)
weight gain
problems with sleeping
an increase in breast tissue
feeling very tired and lack energy (fatigue)
These side effects happen in fewer than 1 in 100 people (less than 1%). You might have one or more of them. They include:
a severe allergic reaction
decreased appetite or loss of appetite
increased appetite
weight loss
a blockage in your artery, such as a blood clot (embolism)
asthma getting worse
hair loss or hair thinning
testicles getting smaller
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
high level of in the blood
pain and swelling in the joints, usually the big toe (gout)
high levels of fat in the blood (high cholesterol)
difficulty sleeping (insomnia)
problems with sight
ringing in ears (tinnitus)
the feeling of the room spinning or moving around you (vertigo)
feeling your heartbeat in your chest (palpitations)
shortness of breath
nosebleeds
constipation or loose poo (diarrhoea)
being sick (vomiting)
feeling very drowsy
swelling caused by fluid build up in arms or legs (peripheral oedema)
severe shivering (rigors)
acne
skin problems such as redness, itching or a rash
muscle weakness and cramping
kidney changes – you will have regular blood tests to check for this
There isn't enough information to work out how often these side effects might happen:
weakened bones that are fragile and more likely to break (osteoporosis)
an irregular heartbeat that needs treatment
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 get someone pregnant while you are having treatment and for a few months afterwards. Talk to your doctor or nurse about effective contraception before starting treatment. Let them know straight away if your partner becomes pregnant while you're having treatment.
If you are having tests or treatment for anything else, always mention your cancer treatment. For example, if you are visiting your dentist.
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.
You can report any side effect you have to the Medicines and Healthcare products Regulatory Agency (MHRA) as part of their Yellow Card Scheme.
Last reviewed: 08 Aug 2025
Next review due: 08 Aug 2028
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.
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.
Hormone therapy blocks or lowers the amount of hormones in the body to stop or slow down the growth of cancer.
Prostate cancer is cancer that starts in the prostate gland. The prostate gland is found at the base of the bladder and is about the size of a walnut.
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