PARP Inhibitors
PARP inhibitors are used to treat advanced prostate cancer that has spread to other parts of the body and has stopped responding to hormone treatments that lower testosterone.
What are PARP inhibitors?
PARP inhibitors are a type of targeted treatment used to treat prostate cancer that has:
- spread to other parts of the body and
- stopped responding to treatment that lowers testosterone.
This is called metastatic castrate resistant prostate cancer (mCRCP)
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How do PARP inhibitors work?
DNA is found in every cell. It carries the instructions that help cells grow and survive.
Cancer cells often have damaged DNA and problems repairing it properly.
PARP is a protein found in cells that helps repair damaged DNA.
PARP inhibitors block the PARP protein.
When this happens, cancer cells can no longer repair their damaged DNA.
Over time, the damage builds up and the cancer cells can no longer survive.
Normal cells are usually better at repairing DNA, so they are less affected.
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Important things to know
What are the benefits of PARP inhibitors?
If you take a PARP inhibitor, your prostate cancer may take longer to get worse (progress).
When are PARP inhibitors used?
PARP inhibitors may be used to treat metastatic castrate-resistant prostate cancer (mCRPC).
There are two types of PARP inhibitors used to treat metastatic castrate resistant prostate cancer.
- Olaparib
- Talazoparib
Olaparib on its own
You may have olaparib on its own if you:
- Have metastatic castrate-resistant prostate cancer and
- Are having hormone injections or taking relugolix tablets, and
- Have already had hormone tablets, such as abiraterone or enzalutamide, and your prostate cancer has started to grow again
- Have a faulty BRCA gene shown on prostate biopsy testing. This can be found by testing samples from your prostate biopsy
Olaparib with abiraterone
You may have olaparib together with:
- Abiraterone (a hormone tablet), and
- A steroid tablet (prednisone or prednisolone)
If you:
- Have metastatic castrate-resistant prostate cancer, and
- Have not been treated before with hormone tablets such as abiraterone, apalutamide, enzalutamide, or darolutamide, and
- Cannot have, or do not want to have, chemotherapy, and
- Live in England, Scotland, or Wales
This treatment is not currently available in Northern Ireland.
Talazoparib
You may have talazoparib if you:
- Have metastatic castration-resistant prostate cancer and
Talazoparib would be your first treatment for metastatic castration-resistant prostate cancer and
You are having hormone injections or relugolix tablets, and
- You are taking enzalutamide tablets, and
- You cannot have chemotherapy and
You are unable to take abiraterone plus prednisolone
You live in England, Scotland or Wales. It is not currently available in Northern Ireland.
You do not need to have a BRCA gene fault to receive Talazoparib
Frequently asked questions about PARP inhibitors
What are BRCA genes?
What are genes?
- Genes are found inside cells and are made up of DNA.
- They are carried from one generation to the next.
- They control how our body grows and works.
- They are also responsible for things like hair and eye colour.
You get genes from both of your parents.
What are BRCA genes?
- BRCA genes are important in the fight against cancer.
- Sometimes genes can carry faults (mutations). These can be inherited from your parents.
- If the BRCA genes get a fault it can increase your chance of getting:
- Breast or ovarian cancer if you are a female.
- Prostate cancer if you are a male.
Do I need to find out if I have a faulty BRCA gene before I can be treated with PARP inhibitors?
If you have not been treated with hormone tablets before:
You do not need to be tested.
If you have had hormone tablets before:
Tissue from your prostate biopsy or sometimes a blood test, can be used to check for faulty BRCA genes. The blood test is not routinely available on the NHS.
If you have not had a biopsy before:
Your doctor might advise you to have one. This will be used to check your cancer for a faulty BRCA gene.
Only about 1 in 5 people with prostate cancer will show a faulty BRCA gene.
What is castration resistant prostate cancer?
Sometimes prostate cancer starts to grow again, even when hormone injections or relugolix are keeping testosterone levels low. This is called Castration-resistant prostate cancer.
It may also be called hormone-relapsed prostate cancer.
It is diagnosed when you are on hormone injections or relugolix tablets and your blood tests show:
Your testosterone level is very low and
Your PSA is rising on three blood tests in a row
or your scans show:
- Two or more new spots of prostate cancer in your bones or
- One new spot of prostate cancer in any other body organ.
Who will give me my prescriptions for PARP Inhibitors?
- PARP inhibitors are usually prescribed by your Oncologist.
- You can ask your hospital team for more information.
How often do I take PARP inhibitors?
Olaparib
- Olaparib is taken as a tablet.
- You take two tablets twice a day.
- This is usually 12 hours apart.
Talazoparib
- Talazoparib is taken as a tablet.
- You take one tablet a day.
Will I have pain during or after treatment?
PARP inhibitors are tablets taken by mouth. They should not cause you any pain.
Do I need to have any tests while I am taking PARP inhibitors?
If you are taking Olaparib on its own, you will need to have: 
- Regular blood tests to check for:
- Anaemia (low red blood cell count) or,
- Any problems with your liver and kidneys.
- Regular PSA tests.
If you are taking Olaparib with Abiraterone and Prednisolone, you will need:
- Your blood pressure checked at least once a month at first.
- A blood test to check your:
- Kidney function and
- Blood potassium and
- liver function
- These will happen every two weeks for the first three months of treatment. Then they will change to monthly. As time goes on, the time between tests may change again.
If you are diabetic, your blood glucose will be monitored. This is to check for low blood glucose.
- You may need scans to check how your cancer is doing or how treatment is working.
If you are taking Olaparib with Abiraterone and Prednisolone, you will need:
You will have a blood test every month to check for:
Anaemia (low red blood cells)
Low white blood cells (which help fight infection)
Low platelets (which help your blood clot)
Regular PSA tests
You may need scans to check how your cancer is doing or how treatment is working
Do I need to take time off work?
- You will be able to continue working if you feel able to do so.
You will need to take time off work for regular outpatient appointments.
How will I know if my PARP inhibitor is working?
You will have regular PSA blood tests. If your PARP inhibitor is working, your PSA will either:
- Lower or
- Stop going up as quickly as it was before taking the PARP inhibitor.
What happens if my PARP inhibitor stops working?
If your PARP inhibitor
- Stops working, or
- You cant take it due to side effects.
Other treatments may be available. These will depend on what treatments you have had before and how well you are.
Possible treatments could be:
Chemotherapy (Visit our page on chemotherapy)
Radium 223 (Visit our page on Radium 223)
Low dose steroid tablets.
Will I still be able to have children?
- You must not father a child while taking PARP inhibitors and for a period of time after treatment ends.
- It is not known whether PARP inhibitors go into your semen.
While you are taking PARP Inhibitors
- You must use a condom when having sex with a female, even if she is already pregnant.
- Your female partner must also use a suitable method of contraception.
- You must not donate sperm
After finishing treatment
- For olaparib, you will need to use contraception for three months after your last dose.
- For talazoparib, you will need to use contraception for four months after your last dose.
About this information
- This information was updated in February 2026. Date of next review: February 2028.
- References and bibliography available on request.
- If you want to reproduce this content, please see our Reproducing Our Content page.
What is risk?
- Risk is the chance something bad could happen when we do something. Even simple things such as walking down the stairs can have risks. But we take risks because we think it will be worth it. We need to think about both the benefits and risks of what might happen when we do something.
- You should always ask your healthcare team about both the benefits and risks of any treatment.
- Remember if they tell you about a risk, it doesn‘t mean it will happen to you. They may say one man in ten who has this treatment will have a side effect. But they can‘t tell you if you will be the ‘one’ man who gets this side effect.
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What are the side effects of PARP inhibitors?
What are the risks of taking Olaparib?
Side effects you should report straight away:
Signs of a possible blood clot (thrombosis or embolism)
painful swollen leg (or arm)
chest pain
sudden or worsening shortness of breath
fast breathing or fast heartbeat
If you have these symptoms, contact your healthcare team urgently. If you cannot reach them, call NHS 111 for advice. In an emergency, call 999 or go to A&E.
Side effects you should report to your healthcare team
Feeling short of breath
Feeling very tired
Pale skin
feeling dizzy or light headed
These symptoms may mean that you have a low number of red blood cells. This is called anaemia. If your symptoms are sudden, severe or getting worse contact your healthcare team straight away. Very common side effects of Olaparib
Affects MORE THAN
Other very common side effects:
• Feeling sick (nausea)
• Being sick (vomiting)
• Feeling tired or weak
• Indigestion or heartburn (dyspepsia)
• Loss of appetite
• Headache
• Changes in taste of foods (dysgeusia)
• Feeling dizzy
• Cough
• Shortness of breath
• Diarrhoea - if it gets severe, tell your doctor straight away.
Very common side effects that may show up in blood tests:
• Low white blood cell count (leukopenia or neutropenia) which may decrease your ability to fight infection and may be associated with fever.
Common side effects
Affects up to
- Rash or itchy rash on swollen, reddened skin (dermatitis)
- Sore mouth (stomatitis)
- Pain in the stomach area under the ribs (upper abdominal pain).
Common side effects that may show up in blood tests
- Decrease in the number of platelets in the blood (thrombocytopenia). These help your blood to clot. You may notice the following symptoms:
- Bruising or bleeding for longer than usual if you hurt yourself
- Low white blood cell count (lymphopenia) which may decrease your ability to fight infection. You may get a fever
- Increase in blood creatinine - this test is used to check how your kidneys are working
Electronic Medicine Compendium (EMC)
- The EMC contains the most up-to-date, approved and regulated prescribing and patient information for all UK licensed medicines.
- You can find more information about the side effects of this treatment in the leaflet that comes with your medicine or from the Electronic Medicines Compendium (this link will open in a new tab).
- You can see the official patient information leaflet for Olaparib (Lynparza) (this link will open in a new tab).
What are the risks of taking Talazoparib?
Side effects you should report straight away:
Signs of a possible blood clot (thrombosis or embolism)
- painful swollen leg (or arm)
- chest pain
- sudden or worsening shortness of breath
- fast breathing or fast heartbeat
Signs of a possible infection (due to low white blood cells)
- fever or feeling hot
- chills or shivering
- feeling unwell with signs of infection
If you have these symptoms, contact your healthcare team urgently. If you cannot reach them, call NHS 111 for advice. In an emergency, call 999 or go to A&E.
Side effects you should report to your healthcare team
- Feeling short of breath
- Feeling very tired
- Pale skin
- feeling dizzy or light headed
These symptoms may mean that you have a low number of red blood cells. This is called anaemia. If your symptoms are sudden, severe or getting worse contact your healthcare team straight away.
Signs of low platelets:
- bruising more easily than usual
- bleeding for longer than usual if you hurt yourself
Very common side effects
Affects MORE THAN
- Decreased appetite
- Feeling dizzy
- Headache
- Feeling sick (nausea)
- Being sick (vomiting)
- Diarrhoea
- Pain in the abdomen
- Hair loss Other very common side effects:
Very common side effects that may show up in blood tests:
- Low white blood cell count (leukopenia or neutropenia) which may lower your ability to fight infection and may be associated with fever.
- Low blood platelets which may make you bruise more easily or bleed more easily or for longer when you cut yourself
- Low red blood cells (anaemia)
Common side effects
Affects up to
- Alteration in taste (dysgeusia)
- Indigestion
- Mouth inflammation
Common side effects that may show up in blood tests
- Decrease in the number of platelets in the blood (thrombocytopenia). These help your blood to clot. You may notice the following symptoms:
- Bruising or bleeding for longer than usual if you hurt yourself
- Low white blood cell count (lymphopenia) which may decrease your ability to fight infection. You may get a fever
- Increase in blood creatinine - this test is used to check how your kidneys are working
Electronic Medicine Compendium (EMC)
- The EMC contains the most up-to-date, approved and regulated prescribing and patient information for all UK licensed medicines.
- You can find more information about the side effects of this treatment in the leaflet that comes with your medicine or from the Electronic Medicines Compendium (this link will open in a new tab).
- You can see the official patient information leaflet for Talazoparib (Talzenna) (this link will open in a new tab).
Where does this information on risk come from?
- The information on the risks comes from very large clinical studies. These typically involved thousands of people being watched over many years.
- There may be local data from your area. You can ask your healthcare team if they have this information too
About this information
- This information was published in April 2024. Date of next review: February 2028.
- References and bibliography available on request.
- If you want to reproduce this content, please see our Reproducing Our Content page.
What is the impact?
- We asked real visitors to the infopool to share their experience of this treatment. They told us how this treatment had impacted their everyday lives in a number of different areas.
- The numbers and images below represent how many people said this treatment had impacted them ‘a lot’ in each of the different areas.
- For example, imagine it says ‘25 in 100’ underneath ‘physical and social wellbeing’. This means that 25 out of 100 people who shared their experience of this treatment told us it impacted their ‘physical and social wellbeing’ a lot. However it would also mean that 75 out of 100 people said it had not impacted them a lot.
Please note: Olaparib is still a fairly new treatment. This means that we do not as yet have enough stories to feed into the images. The images will update as more people share their stories about being treated with Olaparib.
Physical and social wellbeing
Enjoying activities such as walking or going out to the pub
100 out of 100
Effect on relationships
Ability to make good connections with others
100 out of 100
Sexual activity
Ability to reach sexual arousal, either physically or emotionally
100 out of 100
Sense of self
Knowing who you are and what motivates you
100 out of 100
Wellbeing and quality of life
Feeling good and functioning well in your personal and professional life
100 out of 100
Mental and emotional health
Ability to think clearly, make good decisions, and cope with your emotions
100 out of 100
Fatigue
Feeling of constant physical and/or mental tiredness or weakness
100 out of 100
