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Originally published August 25, 2026
Last updated August 25, 2026
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Many of us know someone who’s faced side effects of cancer treatment, like hair loss or debilitating nausea. Their experiences can make us wonder whether everyone experiences these exact same effects.
But Elizabeth Zhang-Velten, MD, PhD, a radiation oncologist with the USC Norris Comprehensive Cancer Center, part of Keck Medicine of USC, says this isn’t necessarily so.
Ahead, Dr. Zhang-Velten explains some of the side effects of radiation therapy and how health providers today have plenty of strategies for managing and even minimizing the side effects of radiation.
Radiation therapy has been a frontline cancer treatment for 100-plus years. By directing high-energy radiation onto cancerous tumors, it damages tumor DNA and stops cancer cells from dividing, growing and spreading.
But the same damage that defeats cancerous tumors can affect healthy cells nearby. That’s why we feel side effects from radiation treatment.
“You’re directing a lot of energy to that area,” Dr. Zhang-Velten explains. “The difference is that while cancer cells don’t have the same quality-control ability to fix radiation damage, your body’s normal tissues are smart and can sense the damage and fix it.”
Radiation’s side effects are localized to the area receiving the radiation.
This distinguishes radiation’s side effects from chemotherapy’s side effects, which may affect other parts of the body, such as with hair loss. During radiation therapy, Dr. Zhang-Velten says, you won’t lose hair on your head unless the treatment is directed there.
The exception to this localized rule is the general fatigue that radiation can cause. And again, the reason traces back to DNA damage: As your body’s healthy cells repair their DNA, Dr. Zhang-Velten says, “they’re using energy to fix themselves, and that can cause whole-body fatigue.”
The key strategy for limiting radiation’s side effects involves limiting the body’s exposure to radiation while still treating enough to beat the tumor.
Technology helps doctors do this. In the early days, Dr. Zhang-Velten explains, radiation was so weak that the only way it could squash deep-seated tumors was if treatments delivered high doses to the body’s surface, which notoriously caused burns. Advances like megavoltage linear accelerators (LINAC) “have made it possible to treat deeply without ‘blasting’ the skin,” she says.
Computed tomography (CT) imaging and rotating beams also let radiation oncologists better locate and target tumor sites with minimal damage to surrounding tissues. Treatment teams can even position patients such that the radiation site sits at a slight distance from the rest of the body.
Still, side effects happen. Dr. Zhang-Velten offers a handful of tips for mitigating them, from the top of the body down.
Head and neck
Radiation for cancers of the head and neck can be especially challenging, Dr. Zhang-Velten says, “because there’s just so much precious real estate in that area.”
Damage to the salivary glands can lead to dry mouth, especially at night. If the taste buds are affected, patients may temporarily lose their sense of taste. And treatment can cause radiation mucositis — an irritation inside the mouth and throat that can make swallowing difficult.
“This is when we take a team approach,” Dr. Zhang-Velten says. “I may send patients to speech and swallow” — a rehabilitation service of speech-language pathologists — “or to a dietitian or occupational or physical therapist.”
She also notes that data from randomized clinical trials shows that a specific probiotic can help diminish the effects of radiation mucositis.
Breast
Swelling and skin irritation are common side effects of radiation to the breast, and data supports the use of a topically applied silicone gel to minimize water loss from damaged skin. Prescription gels are available, but Dr. Zhang-Velten often points patients to silicone scar gels available online.
Lung
The side effects of radiation therapy for lung cancer vary according to a cancer’s stage and treatment, Dr. Zhang-Velten says. Focal treatments that are used to treat a limited area sometimes produce few side effects at all.
“But if you’re treating stage 3 lung cancer,” she notes, “you’re treating lymph nodes in the middle of the chest, and those are near the esophagus.” If the esophagus becomes inflamed, she’ll start patients on medicines that numb the area so they can keep eating, as well as a medicine that sticks to ulcers and allows them to heal during radiation.
Pancreas and liver
Irritation of the small bowel can occur during radiation for pancreatic and liver cancer, and that often causes nausea. Dr. Zhang-Velten sometimes premedicates patients with anti-nausea drugs ahead of treatment and will recommend medicines that reduce irritation to the gut’s lining, including over-the-counter options.
Prostate, cervix, uterus and pelvic area (rectum, anus, vulva)
Diarrhea is a common side effect of radiation here, and Dr. Zhang-Velten says that over-the-counter antidiarrheal products “hold down the fort” for many.
Burns to skin in the pelvic area can occur in patients receiving radiation for anal cancer and vulvar cancer and can be quite painful, however, especially during bowel movements. Management strategies include gentle skincare and the use of barrier creams and use of a peri bottle rather than abrasive toilet paper.
No matter what side effects a patient encounters, Dr. Zhang-Velten collaborates with her Keck Medicine colleagues to improve her patients’ experiences, often referring them to palliative care for further relief. “The rockstar physicians in palliative care really have expertise in managing common side effects like pain, nausea and others,” she says.
And that’s an outcome that suits everybody. “No one comes to my clinic by choice because no one chooses to have cancer,” Dr. Zhang-Velten says. “But they’ve chosen us as part of their care team, and we do what we can to make their radiation treatments personalized and as pleasant as possible.”
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