Understanding Lu-177 PSMA Therapy
Lu-177 PSMA therapy, also called radioligand therapy (RLT), uses a radioactive molecule that seeks out and binds to a protein called PSMA (prostate-specific membrane antigen). This protein sits on the surface of most prostate cancer cells. Once the molecule finds a cancer cell, it delivers a targeted dose of radiation directly to that cell. Because the radiation travels only a very short distance, it is designed to spare most healthy tissue nearby.
Like all cancer treatments, Lu-177 PSMA therapy can cause side effects. The overall picture from clinical research is reassuring. A comprehensive review of Lu-177 PSMA therapy in mCRPC found that "this type of therapy is generally safe, with a low toxicity profile." Most side effects are mild to moderate. Severe side effects are much less common.
Knowing what to expect, and what your care team will watch for, helps you prepare. This guide covers the most common side effects found in real-world patients, along with the strategies doctors use to manage them.
To learn more about how this therapy works, see our related article: What Is Lu-177 Therapy? A Patient-Friendly Guide to How It Works, What to Expect, and Whether It Might Be Right for You.
What the VISION Trial Tells Us About Side Effects
The VISION trial is the most important clinical study of Lu-177 PSMA therapy to date. It was a large, international, randomised Phase 3 trial that compared Lu-177 PSMA therapy (plus standard of care) against standard of care alone in men with PSMA-positive mCRPC.
The trial showed real survival benefits and gave us the most detailed picture of side effects in a large patient group. The National Cancer Institute reported that the treatment was considered "a relatively safe treatment" overall. Most side effects did not require stopping therapy.
A later safety analysis of the VISION trial found that longer exposure to Lu-177 PSMA therapy was not associated with a higher toxicity risk, and the evidence supports a favourable benefit-risk profile for up to 6 cycles of treatment.
Research published in the Journal of Nuclear Medicine (NIH/PMC) confirmed that across both the TheraP and VISION trials, Lu-177 PSMA-617 "had a good safety profile, with common adverse events being fatigue, nausea, dry mouth, marrow suppression and diarrhea."
For a closer look at what the clinical trial results mean for your treatment, read: What Do the Latest Clinical Trial Results Tell Us About Lu-177 PSMA Therapy for Stage 4 Prostate Cancer?
The Most Common Side Effects — and What They Feel Like
Every patient is different. Not everyone gets every side effect. But certain side effects come up repeatedly across real-world studies. Here is what patients most often report.
1. Fatigue
Fatigue is one of the most reported side effects. It is a deep tiredness that rest may not fully relieve. In one retrospective study of older patients treated with Lu-177 PSMA, fatigue was reported in 33% of patients.
Fatigue can come from several causes: the radiation itself, anaemia (low red blood cells), or the burden of a serious illness. It tends to peak in the days after each infusion and then gradually ease before the next cycle.
Doctors manage fatigue by checking blood counts regularly, treating anaemia if present, and discussing activity pacing with patients. Light physical activity and good sleep habits may also help. For more on managing fatigue during radioligand therapy, see our related article: Managing Fatigue During Lu-177 Therapy: What Patients Can Actually Do.
2. Dry Mouth (Xerostomia)
Dry mouth is a side effect specific to PSMA-targeted therapy. The reason is straightforward: PSMA is found not only on prostate cancer cells but also in the salivary glands. According to the National Cancer Institute, "dry mouth is an expected side effect of Lu177-PSMA-617 because the salivary glands are one of the normal tissues where PSMA tends to be produced."
In most patients, dry mouth is mild (Grade 1) and manageable. Real-world data from Indiana University presented at the 2024 ASCO Annual Meeting found that 37% of patients experienced dry mouth during treatment. In the majority of published studies, dry mouth does not reach a severe grade.
Some research has suggested that patients who develop dry mouth or dry eyes during Lu-177 PSMA therapy may have better PSA responses. This may be because these side effects signal that the therapy is being taken up effectively by PSMA-expressing tissue.
How doctors manage dry mouth:
- Frequent sips of water throughout the day
- Saliva substitute sprays or mouth rinses
- Good oral hygiene — brushing, flossing, and regular dental checks
- Avoiding alcohol, caffeine, and tobacco, which can worsen dryness
- Chewing sugar-free gum to stimulate saliva
Dry eyes can accompany dry mouth. Eye drops (artificial tears) are usually recommended for comfort. Tell your care team if these symptoms interfere with eating, sleeping, or daily life.
3. Nausea and Reduced Appetite
Nausea is another common side effect, though it is usually mild and short-lived. It typically occurs in the first day or two after an infusion and then settles. Loss of appetite (anorexia) may also occur.
Nausea is consistently noted across multiple studies of Lu-177 PSMA therapy. Grade 3–5 nausea and vomiting remain uncommon.
How doctors manage nausea:
- Anti-nausea medications (anti-emetics) given before and after treatment
- Small, frequent meals rather than large ones
- Staying well hydrated
- Ginger-based drinks or lozenges, which some patients find helpful
4. Blood Count Changes (Bone Marrow Suppression)
This is the side effect doctors watch most carefully. The bone marrow, where blood cells are made, can absorb some radiation during treatment. This may lower red blood cell counts (causing anaemia), white blood cell counts (raising infection risk), and platelet counts (raising bleeding risk). The medical term for this group of effects is myelosuppression.
Data from the VISION trial showed that severe (Grade 3–5) bone marrow suppression occurred in 23.4% of patients who received Lu-177 PSMA therapy, compared to 6.8% in the control group. This is the most significant Grade 3–5 toxicity signal from the trial.
Several points help put this number in context:
- Many men with mCRPC already have some degree of bone marrow involvement from their cancer before treatment starts.
- The degree of myelosuppression did not worsen with additional cycles. The VISION safety sub-study (published in PMC) found "no additional safety concerns were reported for patients who received more than 4 cycles."
- Compared to chemotherapy options such as docetaxel or cabazitaxel, bone marrow toxicity from Lu-177 PSMA therapy is generally considered less severe.
How doctors manage blood count changes:
- Regular blood tests before and between each cycle
- Blood transfusions if haemoglobin drops significantly
- Growth factor injections to support white blood cell production, if needed
- Delaying the next cycle if counts are too low to proceed safely
- Adjusting the treatment plan in patients with pre-existing kidney problems, as reduced kidney function may affect marrow health
Tell your care team right away if you notice unusual bruising, bleeding, signs of infection (fever, chills, sweating), or extreme shortness of breath.
5. Kidney (Renal) Effects
The kidneys help clear the radioligand from the body, so kidney function is monitored closely throughout treatment. Severe kidney toxicity is uncommon in clinical practice.
In the VISION trial, Grade 3–5 kidney effects occurred in 3.4% of patients in the Lu-177 PSMA arm, compared to 2.9% in the control arm. The VISION dosimetry sub-study confirmed that cumulative kidney radiation doses were within safe limits for most patients.
Doctors typically require a minimum kidney function level before starting treatment. If kidney function is reduced, closer monitoring is recommended, and the treatment plan may need adjustment.
How doctors monitor kidney health:
- Baseline kidney function tests (creatinine, GFR) before starting therapy
- Repeat tests before each cycle
- Adequate hydration before and after infusions
- Avoiding other medications that can stress the kidneys during treatment
6. Bone Pain Flare
Some men with bone metastases notice a temporary increase in pain in the days after an infusion. This is sometimes called a "bone pain flare." It can be unsettling, but it may be a sign that the treatment is working.
When the radioligand reaches bone metastases, it can cause temporary local inflammation and swelling, which briefly increases pain. If the treatment is effective, the pain typically settles within a few days to a couple of weeks.
How doctors manage bone pain flare:
- Reassurance that the flare is often a short-term effect
- Pain relief medications as needed during the flare period
- Monitoring to distinguish a true flare from new or worsening disease
If you have bone pain that is severe or does not settle, always contact your care team. For more on bone pain and Lu-177 PSMA therapy, see: My Bone Metastases Are Causing Severe Pain — Can Lu-177 PSMA Therapy Help?
Less Common but Important Side Effects
A small number of patients may experience other side effects. These include:
- Diarrhoea: Usually mild and manageable with dietary adjustments and anti-diarrhoeal medication if needed.
- Constipation: More common in patients also taking opioid pain relief. Increased fluid and fibre intake, or laxatives, may help.
- Dry eyes: Managed with lubricating eye drops. Persistent dry eyes should be reviewed by an eye specialist.
- Anaemia requiring transfusion: In a small proportion of patients, anaemia from bone marrow suppression may require a blood transfusion. The treating team monitors for this and addresses it as needed.
Radiation Safety at Home
Because Lu-177 emits low-level radiation after the infusion, patients receive specific instructions about radiation safety at home for the first few days after each cycle. These typically cover close contact with young children, pregnant women, and pets.
These precautions are temporary and usually last only a few days. For full guidance on what to expect at home after an infusion, see: Can I Hug My Grandchildren After a Lutetium Infusion?
How Doctors Monitor for Side Effects During Treatment
Monitoring is a central part of Lu-177 PSMA therapy. A well-run programme involves:
- Blood tests before every cycle to check blood counts and kidney function
- Assessment of symptoms — fatigue, mouth dryness, nausea, pain — at each visit
- Imaging scans (typically PSMA PET/CT) to assess treatment response
- PSA measurements to track tumour activity
- Open communication between the nuclear medicine team, your oncologist, and you
If monitoring shows that side effects are becoming hard to manage, your team may delay a cycle, adjust supportive care, or in rare cases reassess whether continuing therapy is in your best interest.
What Makes Some Patients More at Risk?
Not everyone faces the same risk of side effects. Factors that may increase your risk include:
- Widespread bone metastases, which may reduce marrow reserve
- Reduced kidney function before starting treatment
- Multiple prior lines of chemotherapy
- Low blood counts at baseline, before treatment begins
Your care team will assess these factors before recommending therapy. If you are concerned about your eligibility or risk level, see: Am I a Candidate for Lu-177 PSMA Therapy? A Plain-Language Guide to Eligibility.
Putting the Side Effects in Perspective
Men who reach the point of needing Lu-177 PSMA therapy typically have advanced cancer that has progressed despite hormone therapy and often chemotherapy. The alternatives at that stage, including further chemotherapy, carry their own significant side effect burden.
Research comparing Lu-177 PSMA therapy to chemotherapy suggests that the bone marrow toxicities from Lu-177 PSMA therapy are generally "not to the degree that typically cabazitaxel or docetaxel produces." For many patients, the manageable side effect profile is one of the therapy's key advantages.
Real-world studies in older patients, some in their eighties and nineties, found Lu-177 PSMA therapy to be generally tolerable, with clinical benefit seen in a meaningful proportion of patients.
When to Talk to Your Doctor
Contact your care team promptly if you experience any of the following during or after treatment:
- Fever, chills, or signs of infection
- Unusual bruising or bleeding
- Severe or worsening bone pain that does not settle
- Extreme tiredness that stops you from doing daily tasks
- Dry mouth or dry eyes that interfere with eating, swallowing, or vision
- Nausea or vomiting that is not controlled by medication
- Any new or concerning symptoms between cycles
Side effect management is a partnership. The more openly you communicate with your team about what you are experiencing, the better they can support you through treatment.
This article is for general information and is not a substitute for medical advice. Always consult your oncologist or care team about your specific situation.
Frequently asked questions
Is Lu-177 PSMA therapy harder on the body than chemotherapy?
For most patients, Lu-177 PSMA therapy causes fewer and less severe side effects than chemotherapy drugs commonly used in advanced prostate cancer, such as docetaxel or cabazitaxel. Fatigue, dry mouth, and mild blood count changes are the most common issues. Severe bone marrow suppression does occur in a proportion of patients but is generally considered less frequent and less intense than what chemotherapy typically produces. That said, every patient is different, and your own risk depends on your baseline health, kidney function, and how much prior treatment you have had.
How long do side effects from Lu-177 PSMA therapy last?
Most side effects are short-lived. Nausea and fatigue tend to peak in the first few days after each infusion and gradually ease before the next cycle. Dry mouth may persist across cycles but is usually mild. Blood count changes are monitored closely and tend to recover between cycles. In general, side effects do not worsen with additional cycles in most patients — clinical data from the VISION trial showed no increase in toxicity risk between cycles one through six.
What is the most serious side effect of Lu-177 PSMA therapy?
The most clinically significant side effect is bone marrow suppression — a reduction in red blood cells, white blood cells, and platelets. In the VISION trial, severe (Grade 3 or above) bone marrow suppression occurred in about 23% of patients receiving Lu-177 PSMA therapy. Some of these patients needed blood transfusions or growth factor injections. This is why blood tests are performed before every treatment cycle. Doctors will delay or adjust treatment if counts drop too low. Reporting any signs of infection, unusual bruising, or extreme fatigue to your care team right away is important.
Can dry mouth from Lu-177 PSMA therapy be treated?
Dry mouth (xerostomia) is a known side effect because the salivary glands naturally express the PSMA protein and absorb some of the radioligand. For most patients it is mild. It is managed with frequent water sips, saliva substitutes, oral rinses, good dental hygiene, and avoiding alcohol and caffeine. There is currently no single proven method to fully prevent salivary gland uptake, though researchers are investigating several approaches. If dry mouth is affecting your ability to eat or swallow, tell your care team — they can refer you to a dietitian or specialist for additional support.
Will I need to stay in hospital after my Lu-177 PSMA infusion?
This varies by country and by the specific centre where you are treated. In many programmes, Lu-177 PSMA is given as a day procedure or requires only a short admission of one to two nights. After discharge, you will be given radiation safety instructions to follow at home for a few days. These typically involve limiting close contact with pregnant women, young children, and pets. Your nuclear medicine team will give you personalised written instructions before you leave the centre.
What blood tests will I need during Lu-177 PSMA therapy?
Before each treatment cycle, you will typically have a complete blood count (CBC) to check red blood cells, white blood cells, and platelets, as well as kidney function tests (creatinine and estimated GFR). Your doctor may also monitor PSA levels and liver function depending on your individual situation. These tests are not just routine paperwork — they directly guide whether your next cycle proceeds on schedule, is delayed, or requires supportive measures such as a blood transfusion or growth factor injection.