When a loved one finishes first-line chemotherapy for ovarian cancer, the oncologist may prescribe a PARP inhibitor as maintenance treatment. Drugs like olaparib (Lynparza) and niraparib (Zejula) are taken by mouth at home, sometimes for one to two years. Their job is to slow or stop the cancer from coming back. Because this treatment happens mostly outside the clinic, caregivers are often the first to notice changes and respond.
This guide covers the most common side effects and what caregivers can do. It is not a replacement for guidance from the oncology team. Use it to ask better questions and spot warning signs sooner.
| Olaparib (Lynparza) | Niraparib (Zejula) | |
|---|---|---|
| Approved maintenance dose | 300 mg twice daily | 200-300 mg once daily (individualized by weight and baseline platelet count) |
| Most commonly reported grade 1-2 effects | Nausea, fatigue, anemia | Nausea, fatigue, thrombocytopenia |
| Key grade 3+ blood count concern | Anemia | Thrombocytopenia (approximately 33.8% in the pivotal NOVA trial) |
| First dose reduction step | 250 mg twice daily | Individualized reduction based on blood count results |
| CBC monitoring emphasis | Regular throughout maintenance | Frequent, especially in first 3 months |
Sources: ASCO Guideline on PARP Inhibitors in Ovarian Cancer; Mirza et al., New England Journal of Medicine, 2016 (NOVA trial)
According to the American Cancer Society, PARP inhibitors work by blocking an enzyme that helps repair damaged DNA inside cells. Cancer cells with a DNA repair defect – such as those with BRCA1 or BRCA2 mutations – are especially vulnerable. Without PARP, these cells cannot fix the damage and often die. Healthy cells use other repair pathways and are not as affected. This is why PARP inhibitors work well for maintenance treatment. They work quietly in pill form, targeting a weakness in remaining cancer cells.
Side Effects Caregivers Report Most Often
Clinical trial data and the ASCO Guideline on PARP Inhibitors identify three main side effects: fatigue, nausea and digestive problems, and blood count changes. Most are worse in the first few weeks and often improve after two to three months. Knowing what to expect helps caregivers stay calm and report changes accurately to the care team.
Fatigue
Both olaparib and niraparib frequently cause fatigue. It can range from mild tiredness to severe exhaustion that gets in the way of daily life. Fatigue during PARP treatment can come from several sources – the drug itself, low red blood cell counts, disrupted sleep, reduced appetite, or stress from a long treatment course. A review in the Journal of Oncology Practice notes that doctors should check for treatable causes first, such as iron deficiency, low vitamin B12, and thyroid problems, before blaming the drug for tiredness.
Caregivers can help by keeping a daily log of energy levels, when fatigue peaks, and whether it is getting better or worse week to week. Schedule hard tasks when energy is highest. Keep a regular sleep schedule. Ask the care team about gentle activities like short walks. Discuss these strategies at the next visit. Clear any new activities with the oncology team based on current blood counts.
Nausea and Digestive Effects
PARP inhibitors commonly cause nausea. A 2024 review lists it among the most common side effects. It is usually worst in the first four to eight weeks and tends to improve. Taking tablets with food at the same time each day may help. Small, bland meals at regular times help in the early weeks of treatment.
Other digestive effects can include vomiting, diarrhea, constipation, and taste changes. If vomiting stops the patient from keeping tablets or fluids down for more than 24 hours, call the care team that day. Track how many episodes happen in 24 hours and whether the patient can hold fluids. The care team can often prescribe anti-nausea medicine without changing the dose. Report loose stools or constipation that does not go away in a few days at the next contact.
Blood Count Changes: What Caregivers Need to Know
Blood count changes are the most serious side effects of PARP inhibitor treatment. The three most relevant are anemia (low red blood cells), thrombocytopenia (low platelets), and neutropenia (low white blood cells). Each drug has a different risk profile, which is why regular blood counts are needed throughout treatment.
Anemia can develop gradually. Caregivers may notice worsening fatigue, paleness in the skin or lips, shortness of breath with minor activity, or a faster heartbeat. Regular blood count monitoring is recommended throughout treatment, with more frequent checks in the early months. If hemoglobin drops below a certain level, the oncologist may pause the dose temporarily or recommend a blood transfusion. Keeping all scheduled blood tests is critical for treatment.
Thrombocytopenia (low platelet counts) is especially linked to niraparib. In the NOVA trial published in the New England Journal of Medicine, grade 3 or higher thrombocytopenia happened in approximately 33.8% of patients taking niraparib 300 mg once daily. Updated prescribing guidance now recommends a starting dose of 200 mg once daily for patients weighing less than 77 kg or with a baseline platelet count below 150,000 per microliter – a change made to reduce this risk. Report easy bruising, small red or purple spots on the skin (petechiae), bleeding gums, or blood in urine or stool. Any of these findings needs a same-day call.
Neutropenia raises infection risk. A fever of 100.4 degrees F (38 degrees C) or higher in someone with low white blood cell counts is a medical emergency. Other warning signs are chills, new areas of skin redness, and unusual tiredness with fever. The oncology team should give you written fever guidelines – including which facility to go to and what to say on arrival. Keep that protocol visible and easy to reach at any hour.
How Dose Adjustments Work
PARP inhibitors have dose reduction options to help patients stay on treatment when side effects get hard to handle. The standard maintenance dose of olaparib is 300 mg twice daily. The first reduction is 250 mg twice daily. A second reduction of 200 mg twice daily is possible if needed. For niraparib, the oncologist sets the starting dose based on weight and baseline platelet count. Further reductions are guided by blood count results.
Dose reductions are not a sign that treatment is failing. They are a standard tool to help patients stay on PARP inhibitor treatment longer. Many patients benefit from the drug at a reduced dose. Caregivers can help by keeping a record of which side effects led to each change, when it happened, and whether symptoms got better. This record helps the oncologist make better decisions at each visit.
Day-to-Day Support Strategies
PARP inhibitor treatment involves three main areas for caregivers: medication management, symptom tracking, and communication with the care team. Tablets should be taken at the right time each day, stored at room temperature away from moisture, and not crushed or split unless the pharmacist says it is safe. Report missed doses to the clinic, as different drugs have different rules about what to do next.
Tracking symptoms does not have to be complicated. A notebook or app can track energy levels (on a 1-10 scale), nausea, bruising or bleeding, and bowel changes. Bringing this log to every visit gives the team better information and helps caregivers spot patterns you might miss day to day – such as nausea that is worse on certain days, or fatigue that improves with a certain meal schedule.
Pay close attention to nutrition during treatment. Small, frequent meals work better than large ones when nausea is a problem. Snacks with protein help keep muscle mass during the long course. Drink plenty of fluids, especially if diarrhea or vomiting happens. Report any unexpected weight loss right away to the care team, as it can affect how well treatment works.
When to Contact the Care Team
Some symptoms need a same-day call. Others can wait for the next visit. The following generally need prompt contact:
- Fever of 100.4 degrees F (38 degrees C) or higher
- Unusual or uncontrolled bleeding, including prolonged bleeding from a cut, blood in urine or stool, or unexpected heavy menstrual bleeding
- Shortness of breath at rest or with very mild activity
- Vomiting that prevents the patient from keeping tablets or fluids down for more than 24 hours
- New bruising without a clear cause, or small red or purple spots appearing on the skin
- Sudden severe headache, vision changes, or confusion
Mild nausea that is stable and controlled, mild fatigue that is not getting worse, and minor bowel changes with no blood can be reported at your next visit. Call if you are unsure. Oncology teams prefer early calls over late ones, and most have a nurse line between appointments.
Looking After Yourself as a Caregiver
PARP inhibitor treatment can run for one to two years. Staying close and providing support for that long is exhausting. Caregiver burnout is a known problem, and the care team can help if you bring it up. Strategies for managing long-term caregiver strain – including peer support groups, planned breaks, and sharing tasks with family – are explored in the article on Leukemia Caregiver Burnout During Long-Term Monitoring, which covers patterns common to all long-term cancer treatments.
Caregivers managing multiple ovarian cancer symptoms alongside PARP treatment may find value in the article on Managing Night Sweats After Ovarian Cancer Chemo, which covers hormonal changes from chemotherapy that can continue into the maintenance phase. For caregivers whose loved ones are on a different targeted treatment path, the article on Managing Lapatinib Side Effects in HER2+ Ovarian Cancer provides a parallel reference for that treatment and the caregiver role it requires.
If the oncology team has discussed additional options alongside PARP inhibitor treatment, you can see what Oncostore stocks in the Targeted Therapy category for current pricing and availability.
If you or your loved one takes prescription medicine, is pregnant, or is breastfeeding, talk with a doctor before starting any new supplement or remedy. This article is for general information and is not a substitute for medical advice. Always talk with your oncologist or care team about your specific situation.
