Here’s an overview of how you may feel after external radiation treatments. Which symptoms you have depends mainly on which part of your body is treated:
Your skin in the treated area may become dry, irritated, and sensitive.
You are likely to feel tired or experience a generalized weakness. This tends to increase gradually and becomes worse as radiation treatments continue.
You may get infections, become dehydrated, or have a reduced red blood cell count that leads to anemia, as shown from blood tests. All of these can make being tired worse.
You may have nausea or a loss of appetite.
If you have radiation treatments to your chest or neck, it may damage your salivary glands. That leads to dry mouth called xerostomia. Treatment to these areas may also cause inflammation of the food pipe (esophagus) called esophagitis. That can make it painful to swallow or give you feelings of heartburn.
Radiation of the stomach may cause upset stomach or diarrhea. This is usually a temporary effect.
You may have hair loss in the area being treated. Although this is generally temporary, higher doses may make hair loss permanent. You won’t experience the kind of hair loss—over the whole head—that is common with chemotherapy unless your whole head is treated with radiation.
Radiation may worsen the side effects of chemotherapy.
You may have dry eyes.
You may feel better during your radiation treatment if you make an extra effort to get plenty of rest and to eat as well as you can. Most of these side effects get better over time once treatment is over. Long-term side effects of radiation may not show up for several years after your treatments end.
The immediate side effects of total body irradiation can be more severe than for targeted radiation therapy. They include an increased risk for infection from lower white blood cell counts and from damaged skin and mucous membranes.
The main side effects from radioimmunotherapy (internal radiation injected into your blood as a drug) include possible allergic reactions during the infusion and lowered blood cell counts over time.
Ask your doctor which symptoms, if any, require that you call him or her right away. For instance, it is wise to call your doctor if you have signs of infection, such as fever or pain.
Radiation can also sometimes cause damage that may not show up as side effects until months or years after treatment. Depending on where the radiation was aimed, these can include lung or heart damage (from radiation to the chest), damage to the thyroid gland (from radiation that reaches the neck), headaches or memory loss (from radiation to the head), and an increased risk of developing other cancers.