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by C.H. Weaver M.D. updated 5/2022

Shielding your skin from the sun’s potentially harmful ultraviolet (UV) rays should be a concern for everyone, especially if you spend time outdoors, but if you’re undergoing treatment for cancer, you may need to be especially vigilant when it comes to sun protection; some of the medications you’ve received may make your skin more vulnerable to UV damage and might also be associated with side effects that can worsen in hot, sunny conditions.

Photosensitivity, or extreme sensitivity to ultraviolet (UV) rays from the sun is a side effect of some medications.1

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Two kinds of photosensitive reactions exist:

  • Phototoxic: During a phototoxic reaction the drug becomes activated by UV rays from the sun and a skin rash similar to a “sunburn” occurs.
  • Photoallergic: A photoallergic reactions is an actual allergic reaction to the medication that results from UV exposure which alters the structure of the drug so that the immune system views it as an antigen causing an allergic response.

Know the Risks

Consult your healthcare team about the treatments you have or are receiving and how they might make your skin more sensitive to the sun. Chemotherapy, radiation, and other cancer therapies may cause skin irritations, making you more vulnerable to UV damage. Be aware as well that cancer treatment—particularly chemotherapy—can cause thinning or loss of hair, which could leave your scalp unprotected under the sun’s rays. Also keep in mind that due to other side effects of treatment—such as diarrhea and nausea—you may not be consuming enough fluids and are therefore at risk for dehydration. A hot summer climate could make it more difficult to stay hydrated.

Tips for Safe Summer Fun

Though the concerns above are serious considerations for anyone undergoing cancer treatment, you can take a few extra precautions that will help you enjoy your time outdoors with added safety. Before you venture out, however, it’s important to consult your physician to make sure there are no additional risks associated with your planned outing and to ensure that you’re proceeding as safely as possible. Your healthcare provider may have some advice to add to the following tips:

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Avoid direct sunlight

Seeking shade—whether natural, such as under a tree, or creating your own with an umbrella, awning, or other shelter—will reduced your exposure to UV rays. Protective clothing and accessories—such as long pants, long-sleeved shirts, scarves, and wide-brimmed hats— will also boost safety by covering your skin. Look for clothing made of fabrics with a UPF (ultraviolet protection factor) rating for added protection. Large-frame sunglass with UV-protective lenses can help shield your eyes and surrounding area. Be aware that the sun’s rays are most powerful, and therefore most dangerous, between the hours of 10 a.m. and 4 p.m.—it’s wise to limit sun exposure during this time.

  • Limit time spent outside when the sun is at its peak around midday
  • Wear long pants, long sleeves, and a hat with a wide brim

Step up your hydration

Staying hydrated is a common guideline for general wellness, but becomes even more important during hotter summer months when you may lose more fluids and electrolytes through perspiration. And if cancer treatment is making it particularly difficult for you to stay hydrated, you’ll want to pay close attention to your fluid intake as temperatures rise. One common guideline is to try to drink at least eight ounces (one cup) of water every hour from the time you wake up until you fall asleep. Your healthcare team may have more personalized advice for your individual needs and the environment in which you live.

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Preventive Measures to Protect Your Skin

Because cancer therapies may have made your skin more sensitive in general, not just to the sun, it’s important that you consult your healthcare provider before applying any lotions or cosmetics to your skin, sunscreen included. Certain sunscreen chemicals and formulations may cause irritation or pose other risks. Also talk with your healthcare team about the most effective way to apply sunscreen. Common guidelines include using ample amounts of the product and reapplying regularly, particularly after swimming or perspiring.

  • Use sunscreen with a sun protection factor (SPF) of 30 or above
  • Use water-resistant sunscreen if swimming or sweating profusely
  • Reapply sunscreen very 3 hours
  • Apply sunscreen on the lips (some products are formulated for this use)


  1. Cunha JP. Sun-sensitive drugs (photosensitivity to drugs). MedicineNet. Reviewed April 26, 2018. Accessed July 25, 2019.
  2. Levine B. Rheumatoid arthritis medication: beware of sunburn if you take these drugs. Everyday Health. Updated May 15, 2017. Accessed July 25, 2019.
  3. Sun allergy (photosensitivity). Harvard Health. Published October, 2018. Accessed July 25, 2019.