Chemotherapy cream, most commonly a drug called fluorouracil (often shortened to 5-FU), works by soaking into abnormal skin cells and blocking their ability to make new DNA. Because precancerous and cancerous cells divide much faster than normal skin cells, they absorb more of the drug and are hit hardest. Over a treatment course of two to six weeks, those damaged cells die off while healthy surrounding skin largely recovers on its own.
What the Cream Actually Does to Skin Cells
Fluorouracil mimics one of the building blocks cells need to copy their DNA. When a rapidly dividing cell absorbs the drug, it tries to use it during cell division, but the process fails. The cell can’t complete replication and dies. Normal skin cells divide slowly enough that they take in far less of the drug, which is why the cream selectively targets the problem areas while sparing most of the healthy tissue around them.
A second type of chemo cream uses a different approach entirely. Instead of poisoning cells directly, it activates your immune system. This cream prompts immune cells to recognize and attack abnormal growths on the skin’s surface. It’s prescribed for many of the same conditions and is especially effective against superficial basal cell carcinoma, with five-year success rates around 80%.
What It’s Prescribed For
The most common reason doctors prescribe chemo cream is actinic keratosis, those rough, scaly patches caused by years of sun exposure that can eventually turn into squamous cell carcinoma. The cream treats an entire area at once rather than freezing or scraping individual spots, which makes it particularly useful when someone has many lesions spread across the face, scalp, or forearms.
Fluorouracil is also approved for superficial basal cell carcinoma, the most common form of skin cancer, when it hasn’t grown deeper than the top layer of skin. This use is generally reserved for cases where surgery or other standard treatments aren’t a good option.
How a Typical Treatment Course Works
For actinic keratosis, the standard routine is applying a thin layer of cream to the affected area twice a day for two to four weeks. For superficial basal cell carcinoma, the same twice-daily schedule extends to three to six weeks. You apply just enough to cover the treatment area and gently rub it in, usually with a fingertip or non-metal applicator, then wash your hands thoroughly.
The treatment area should stay uncovered unless your doctor says otherwise. You’ll need to be careful about sun exposure, since the treated skin becomes significantly more sensitive to UV light. Broad-spectrum sunscreen and protective clothing over the area are important throughout treatment and for some time afterward.
What Your Skin Goes Through During Treatment
The skin reaction during treatment follows a predictable pattern, and understanding it helps because the process can look alarming if you’re not expecting it. The stages unfold roughly in this order: redness, then blistering, then peeling and flaking, then raw or eroded skin, and finally healing with new skin forming underneath.
The first few days, you may notice mild redness and irritation. By the end of the first week, the areas with the most sun damage start to become noticeably inflamed, sometimes turning bright red or forming small blisters. This is the cream revealing damage that was already there, even spots you couldn’t see yet. The worse the reaction looks, the more precancerous cells were lurking in that area.
Weeks two through four are usually the most uncomfortable. The skin can become raw, crusty, and sore. Some people describe a burning or stinging sensation. This is the erosion phase, where damaged cells are dying and sloughing off. It’s tempting to stop early, but completing the full course is important for the best results. Once you finish applying the cream, healing typically takes two to four additional weeks. The new skin underneath is often pink at first but gradually returns to a more normal appearance.
How Well It Works
For actinic keratosis, fluorouracil cream achieves complete clearance of all visible lesions in about 38% of patients at six months, compared to 17% with no active treatment. That number may sound modest, but it reflects total clearance across an entire treatment field. Most patients see a significant reduction in the number and severity of their spots even when some remain. Follow-up treatments or combination approaches can address what’s left.
For superficial basal cell carcinoma treated with the immune-activating cream, results are stronger. In a prospective five-year study, 94% of patients had initial clearance after treatment, and about 80% remained cancer-free at the five-year mark. Of those who did see a recurrence, most happened within the first two years, which is why close follow-up visits are standard during that window.
Other Topical Options
Fluorouracil and the immune-activating cream are the most widely used, but a third option exists for actinic keratosis: an anti-inflammatory gel. This treatment works by reducing the inflammation and cell signaling that help precancerous cells survive. It’s applied twice daily for 90 days, a much longer course than fluorouracil, and tends to cause less dramatic skin reactions. In clinical trials, about 65% of patients saw their lesions shrink, though complete clearance rates were lower at roughly 9%. It’s sometimes chosen for people who can’t tolerate the intense skin reaction that fluorouracil causes.
Practical Tips for Getting Through Treatment
The biggest challenge with chemo cream is sticking with it. The skin reaction is supposed to happen, but it’s uncomfortable and can be cosmetically distressing, especially on the face. A few things can help. Applying petroleum jelly to the skin around the treatment area (but not on it) can protect healthy skin from irritation. A gentle, fragrance-free moisturizer can be used on surrounding areas. Ice packs or cool compresses sometimes ease the burning sensation.
Plan your treatment timing around your schedule if you can. Many people choose a period when they can limit social obligations or outdoor activities. If you’re treating your face, the raw, peeling phase is visible and hard to conceal with makeup, so a stretch of working from home or lighter commitments can reduce stress. Some doctors recommend treating during fall or winter when sun exposure is naturally lower and hats and scarves are already part of the routine.
Avoid touching the treated area and then touching other parts of your body or other people. The cream is a chemotherapy agent, and while the dose is low and localized, it should only contact the skin it’s meant to treat. Wash your hands immediately after every application.