Rashes During Chemotherapy: What to Watch For and When to Act

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Rashes During Chemotherapy: What to Watch For and When to Act

Chemotherapy can impact the body in many ways, including changes to the skin. While rashes might seem like a mild side effect, they can sometimes be early signs of a more serious issue. Understanding what to look for—and when to report symptoms—can help prevent complications.

A Realistic Scenario: When a Rash Is More Than Skin Deep

Imagine this:

A person undergoing chemotherapy notices a painful bump near the lower back or buttock. A red rash starts to develop. Later that day, they begin to feel unwell and spike a fever. Concerned, they visit the emergency department. By the time they're seen, the fever has settled. The rash isn’t mentioned or examined, and they are sent home.

The next morning, the rash has spread significantly—to the buttock, back of the leg, and groin area. It is blistering, red, and extremely painful. Upon returning to clinic and being assessed, a diagnosis of shingles (herpes zoster) is made. Antiviral treatment is started, but the delay in treatment has allowed the condition to worsen.

Why Skin Changes Matter During Chemotherapy

People receiving chemotherapy are often immunocompromised, meaning their bodies can’t fight infections as well. Rashes may result from medications, infections, or treatment side effects—and some require urgent care.

Common rashes during or after chemotherapy include:

Allergic reactions – red, itchy welts or hives
Radiation rash – localized irritation in areas receiving radiation
Targeted therapy rash – acne-like, often on the face, chest, or scalp
Shingles (herpes zoster) – painful, blistering rash on one side of the body
Cellulitis – red, warm, swollen area due to bacterial skin infection

When to Report a Rash Immediately

It’s best to report any rash as soon as possible, especially if it is:

Accompanied by fever, chills, or feeling unwell
Painful, blistering, or rapidly spreading
Warm or swollen, which could indicate infection
Located near the eyes, face, genitals, or covering a large area
In someone with a history of chickenpox or shingles

Timely assessment can lead to faster treatment and may prevent serious complications like nerve pain or infection spread.

Tips for Patients and Caregivers

Report early. Don’t wait for the rash to worsen—call your care team.
Be specific. Describe the location, how it feels (itchy, burning, painful), and when it appeared.
Track changes. Take photos to document how the rash evolves.
Mention other symptoms. Even a mild fever can be significant during treatment.
Over-The-Counter Treatment. Topical creams have been very effective for many rashes especially when they are itchy. Patients have often shared that Aveeno moisturizing lotion to provide good relief for minor itchy skin or mild rash. Steriod creams such as Hydrocortisone 0.5-1% is also available in the allergy aisle of your local pharmacy and as good one to always have in your medication cabinet. These can be applied sparingly and avoid exposure of skin to the sun as you may be more sensitive after applying a steriod cream.

Oral anti-histamines such as Diphenhydramine (also known as Benadryl) or Loratidine (Claritin) are helpful for mild allergic reactions that causes itching, mild rash or flushing. Dihenhydramine does cause drowsiness so often recommended to take at bedtime and to use Claritin in the daytime.

Cotton gloves may help you are having trouble avoiding scratching your itch. Scratching can cause break in your skin which is your body's first line of defence against bacteria and foreign invaders.

Cool baths or showers are also very soothing. For smaller areas a cool compress should suffice.

Final Thoughts

During cancer treatment, even something that appears small—like a rash—can be your body’s way of asking for help. If you notice anything new or unusual, reach out to your care team. Early attention can make all the difference.

A Note on Writing

This reflection was crafted with the assistance of AI, then carefully reviewed, edited, and personalized to reflect my voice and experience. My intent in using this tool is not to replace the human touch, but to strengthen it—allowing me to bring together research, scripture, and lived experience in a way that is both thoughtful and accessible.

With you on your journey,

June Ng-A-Kein Founder, Present Help by June