Can Radiation Therapy Cause Nausea?

Radiation can cause nausea, and it is one of the more common side effects people notice during treatment, though many people never have it. Whether you feel sick depends far less on radiation as such than on which part of your body is in the beam. Radiation acts only where it is aimed, so a person treated for prostate cancer and a person treated for breast cancer can face very different odds. Doctors can usually predict the risk before treatment starts and prevent most of it with medicine.

Where You’re Treated Matters Most

Somewhere between 4 and 8 in 10 people receiving radiation have some nausea or vomiting at some point.1SAGE Journals / PubMed Central. A review on radiation induced nausea and vomiting: “Current management strategies and prominence of radio sensitizers” The range is wide because risk depends on the treated site, the total dose, how the dose is split into sessions, and how large an area is treated.2PubMed. Radiotherapy-induced nausea and vomiting (RINV): MASCC/ESMO guideline for antiemetics in radiotherapy: update 2009

Schedule matters in its own right. Fewer, larger doses to the belly or pelvis can bring on nausea more abruptly than the same total spread across weeks, while a long course of small doses can lead to nausea that builds slowly as the gut lining is affected.

The belly and pelvis carry the highest risk. In one group of patients, about two-thirds of those treated to the lower abdomen or pelvis had nausea, compared with about half of those treated to the head and neck.3PubMed Central. Prophylactic Management of Radiation-Induced Nausea and Vomiting Radiation to these areas can damage the lining of the gut, which shows up as nausea, diarrhea, and trouble absorbing food.4PubMed Central. Single radiation exposure induces gut microbiota dysbiosis and decreases short-chain fatty acid metabolism and intestinal barrier integrity in mice If you are being treated for cancer of the stomach, pancreas, bowel, cervix, or prostate, expect to discuss nausea with your team. Whole-body or large-field radiation, such as the kind given before a bone marrow transplant, carries a very high risk, and teams usually give preventive medicine routinely.

Brain and head-and-neck treatment can also cause it. About 4 in 10 people having brain radiation felt nauseous during treatment, and nearly 9 in 10 of those cases were mild.5PubMed Central. Brain radiotherapy and dorsal vagal complex irradiation: A new organ at risk to decrease radiation-induced nausea and vomiting? A small area at the base of the brain helps control vomiting, and the more radiation it receives, the more likely nausea becomes.6PubMed Central. Brain radiotherapy and dorsal vagal complex irradiation: A new organ at risk to decrease radiation-induced nausea and vomiting? In that group, about 16% of those whose plan kept dose to this area low had nausea, compared with 62% of those whose plan gave it more.7PubMed Central. Brain radiotherapy and dorsal vagal complex irradiation: A new organ at risk to decrease radiation-induced nausea and vomiting? In head and neck cancer, about 4 in 10 had mild nausea and about 1 in 6 had moderate nausea.8Radiotherapy and Oncology. Factors associated with radiation-induced nausea and vomiting in head and neck cancer patients treated with intensity modulated radiation therapy

Radiation to the breast, arms, legs, or skin usually spares both the gut and the brain’s vomiting center. Most people treated in these areas never need anti-nausea medicine. If you do feel sick, it may come from worry, other medicines, or the cancer itself, but mention it anyway.

Radiation teams often sort treatment sites into rough risk groups for nausea, from low to high, and these groups guide how much prevention is planned. The groups are a starting estimate for a typical patient, so your own history and any chemo can move you up or down. Sites in the middle group are where plans vary most: some teams give medicine before every session, others wait to see how you do. It is worth asking your team whether your plan counts as low, moderate, or high risk, whether dose to sensitive areas can be limited (as is done for the brain’s vomiting center), and whether you will get preventive medicine or medicine to take only if needed.

Why Radiation Makes You Feel Sick

Radiation raises levels of serotonin, a chemical messenger, in the lining of the gut and in the brainstem.9PubMed. Neurochemistry and neuropharmacology of emesis – the role of serotonin Cells in the gut lining release serotonin, which activates nearby nerves that run to the brain.10PubMed. Neurochemistry and neuropharmacology of emesis – the role of serotonin Those nerve signals can set off the urge to vomit.11PubMed. Neurochemistry and neuropharmacology of emesis – the role of serotonin That is why medicines that block this serotonin signal are the main treatment for radiation nausea.12US Pharmacist. Management of Radiation-Induced Nausea and Vomiting

Belly radiation acts on the gut cells that release serotonin, while brain radiation can reach the vomiting center directly. Both routes end in the same reflex, which is why the same medicines help. Because gut nerves report to the brain, irritated gut lining can make you nauseated even when food hasn’t upset your stomach.

When Nausea Starts and How Long It Lasts

Nausea can come within 24 hours of a session or later, which is called delayed nausea.13Cancer Therapy Advisor. Managing Chemotherapy- and Radiation Therapy-Induced Nausea and Vomiting Higher single doses tend to bring symptoms on faster and harder.14ASTRO. Chapter 8 – Acute Radiation Syndrome A large one-time dose, such as a treatment for bone pain, can cause nausea within a few hours.

Over a course of daily sessions, many people feel fine in the first days and notice queasiness as sessions add up. It may be worst a few hours after each treatment, and weekends without treatment often bring some relief. Noting how many hours after treatment nausea starts helps your team time your medicine. Nausea from the gut usually settles within a few weeks after the last session.

Delayed nausea can catch people off guard. It can appear on a day with no treatment, so people sometimes don’t connect it to radiation. If you expect nausea only right after a session, you may not mention later symptoms to your team.

Nausea long after treatment ends is not typical. It can come from other medicines, dehydration, or the illness itself, so tell your team and they can look for another cause.

Medicines That Prevent and Treat It

Anti-nausea medicines called serotonin blockers, such as ondansetron (Zofran), control radiation-related vomiting well.15US Pharmacist. Management of Radiation-Induced Nausea and Vomiting Taken in advance, they lowered the chance of vomiting by about 30% and the chance of nausea by about 16% compared with a dummy pill.16PubMed. Prophylaxis of radiation-induced nausea and vomiting using 5-hydroxytryptamine-3 serotonin receptor antagonists: a systematic review of randomized trials They work better against vomiting than against nausea itself.17PubMed. Efficacy of 5-HT3 receptor antagonists in radiotherapy-induced nausea and vomiting: a quantitative systematic review Ondansetron also controlled vomiting better than the older drug metoclopramide (Reglan).18PubMed. Efficacy of 5-HT3 receptor antagonists in radiotherapy-induced nausea and vomiting: a quantitative systematic review

You may still feel a little off even when you are not throwing up. Tell your team if queasiness persists, since other medicines can be added.

Steroids add protection. The steroid dexamethasone, taken in advance, fully protected 70% of patients from vomiting, compared with 49% on a dummy pill.19PubMed. Dexamethasone for the prophylaxis of radiation-induced emesis: a National Cancer Institute of Canada Clinical Trials Group phase III study People taking it reported more trouble sleeping, though.20PubMed. Dexamethasone for the prophylaxis of radiation-induced emesis: a National Cancer Institute of Canada Clinical Trials Group phase III study Adding a short course of dexamethasone to ondansetron gives a modest extra benefit.21PubMed. 5-hydroxytryptamine-3 receptor antagonist with or without short-course dexamethasone in the prophylaxis of radiation induced emesis: a placebo-controlled randomized trial of the National Cancer Institute of Canada Clinical Trials Group (SC19)

Medicine taken before a session usually works better than chasing nausea after it starts. For higher-risk areas, teams often schedule medicine before each session, while for lower-risk areas a prescription to take only if needed is common. Starting prevention early matters most for people who have never had radiation before.22ScienceDirect / Elsevier (Journal of Medical Imaging and Radiation Sciences). An Overview of Radiation-Induced Nausea and Vomiting Ask your team exactly when to take the pill relative to your appointment, and take it then even if you feel well, since the point is to block the signal before it starts.

These medicines have side effects of their own. Ondansetron can cause constipation and headache. Dexamethasone can disturb sleep, so a morning dose is often advised. Tell your team about any other medicines you take before starting.

Chemo Given Alongside Radiation

When chemo is given during the same weeks as radiation, about half of people have at least one bout of nausea and a quarter vomit at least once.23PubMed. Patient- and treatment-related risk factors for nausea and emesis during concurrent chemoradiotherapy How likely the chemo drug is to cause sickness is the strongest predictor of nausea during combined treatment.24PubMed. Patient- and treatment-related risk factors for nausea and emesis during concurrent chemoradiotherapy In nose-and-throat cancer, adding chemo to radiation made nausea and vomiting far more likely than radiation alone.25PubMed Central. Toxicities of chemoradiotherapy and radiotherapy in nasopharyngeal carcinoma: an updated meta-analysis Moderate-to-severe nausea in head and neck cancer was likewise linked to chemo given at the same time.26Radiotherapy and Oncology. Factors associated with radiation-induced nausea and vomiting in head and neck cancer patients treated with intensity modulated radiation therapy

Different chemo drugs carry very different chances of causing nausea, from low to high. A regimen with a drug that commonly causes sickness will usually dominate your nausea picture, regardless of where the radiation is aimed.

Chemo and radiation can each irritate the gut or trigger the vomiting reflex, so their effects can overlap. Chemo alongside radiation to the belly, pelvis, or certain areas of the brain may add to a risk that was already present. Teams often plan prevention around both treatments together. Nausea right after a chemo infusion is often driven mainly by the chemo, so your anti-nausea plan is usually built around that drug as well as the radiation.

Who Is More Likely to Feel Sick

Tell your team about your history, including motion sickness or bad morning sickness even from years ago, and any nausea during past chemo. If you have several risk factors, your team may start preventive medicine sooner.

Between 1.5% and 8% of people feel nausea before a session even starts.33Cancer Therapy Advisor. Managing Chemotherapy- and Radiation Therapy-Induced Nausea and Vomiting The body learns to link the treatment setting with past sickness, especially after nausea that was not well controlled.34Cancer Therapy Advisor. Managing Chemotherapy- and Radiation Therapy-Induced Nausea and Vomiting This kind of nausea responds less well to anti-nausea medicine.35Cancer Therapy Advisor. Managing Chemotherapy- and Radiation Therapy-Induced Nausea and Vomiting

Relaxation, breathing exercises, or distraction before sessions can help. Some people benefit from short-term anti-anxiety medicine prescribed by their doctor. Telling the team early keeps the pattern from setting in.

What You Can Do Yourself

People receiving acupuncture during radiation were more often free of nausea and able to eat normally than those getting standard care.36PubMed Central. Reduced Need for Rescue Antiemetics and Improved Capacity to Eat in Patients Receiving Acupuncture Compared to Patients Receiving Sham Acupuncture or Standard Care during Radiotherapy Fake acupuncture worked just as well as real acupuncture, though.37PubMed Central. Reduced Need for Rescue Antiemetics and Improved Capacity to Eat in Patients Receiving Acupuncture Compared to Patients Receiving Sham Acupuncture or Standard Care during Radiotherapy

Small, frequent meals are easier than large ones, and bland, dry foods like crackers or toast often sit better. Eating something small before treatment can help, since an empty stomach can make queasiness worse for some people. Cold or room-temperature foods smell less than hot ones, which helps if cooking smells put you off. Eat slowly and sit upright for a while afterward. Avoid strong smells and greasy or very spicy food on treatment days, and if one food now repulses you, set it aside rather than forcing it.

Sip fluids through the day rather than drinking a lot at once. When you feel sick, clear drinks, ice chips, or popsicles can be easier than plain water, and small sips every few minutes work better than gulping. Vomiting and poor intake together can lead to dehydration quickly. Nausea can lead people to miss or stop treatment sessions, so report it early rather than toughing it out.38ScienceDirect / Elsevier (Journal of Medical Imaging and Radiation Sciences). An Overview of Radiation-Induced Nausea and Vomiting

Call your care team if you cannot keep fluids down for a day, or if you feel dizzy, are passing little urine, or notice other signs of dehydration. Call if your medicines are not working, since doses or drugs can be changed, and call if vomiting comes with fever, chills, or breathlessness.