Dear Iris,

I’m going through treatment this summer, and I’ve noticed that the heat seems to make everything harder. Some days I feel completely wiped out just from being outside for a little while, and other times I feel like I get overheated quickly. I’m trying to stay active and enjoy being outdoors, but I’m wondering—can the heat actually make side effects worse? Or is this all in my head?

W

Dear W,

You're not imagining it—heat and humidity can absolutely make treatment side effects feel worse. Additionally, certain treatments, including chemotherapy, radiation, or targeted therapies, may cause dehydration, taste changes, nausea, diarrhea, or fatigue—all of which can impact your body’s ability to stay hydrated and regulate body temperature.

That means spending even a short amount of time outdoors can leave you feeling overheated or unusually tired. There are steps you can take to stay safe and feel more comfortable while still enjoying the outdoors. 

Try these “beat-the-heat" tips: 

• Avoid the hottest hours of the day (usually between 10am–4pm) 

• Sip water throughout the day, even if you don’t feel thirsty—hydration is essential during treatment and in the heat

• Wear light, breathable fabrics like cotton or linen 

• Use a portable fan, cooling towel, or misting spray when outside 

• Take regular breaks in air-conditioned spaces to cool your core temperature 

• Add hydrating foods to your meals, like watermelon, cucumbers, or smoothies 

If you feel dizzy, stop sweating, feel confused, or your symptoms don’t improve with rest, it may be a sign of heat exhaustion—cool down right away and reach out to your care team if your symptoms don’t improve. 

You’re not alone in this, and it’s okay to take things slower in the heat. Be kind to your body—it’s working hard.