Fluorouracil Topical (5-FU, Carac®, Efudex®, Fluoroplex®)
Pronounce: FLURE-oh-UE-ra-sil
Classification: Antimetabolite
About Fluorouracil Topical (5-FU, Carac®, Efudex®, Fluoroplex®)
Antimetabolite medications are a type of chemotherapy. Cancer cells need metabolites to make copies of themselves and grow. Antimetabolites look like a certain metabolite. The cancer cells try to use the antimetabolite medication to grow but it does not work, stopping more cancer cells from being made.
This medication is used to treat actinic keratosis and superficial basal and squamous cell skin cancers. The medication destroys sun-damaged skin cells, but can also damage normal skin and cause skin irritation.
How to Use Topical Fluorouracil
This medication is a topical cream, available in 2 strengths. Your provider will determine which strength is right for your condition and tell you how often to use the cream (typically 1-2 times a day). Most patients will use the cream for 2-12 weeks, depending on the condition being treated and the response to treatment.
To apply the cream:
- Wash the area to be treated with plain water and dry it. Wait 10 minutes.
- Wear a glove when applying the medication or use a non-metal applicator.
- If your hands come into contact with the 5-FU, wash them right away.
- Use an amount sufficient to cover the lesions being treated.
- If you need to cover the area, use only a porous gauze dressing that allows the area to "breathe".
- Do not apply to the eye, into the vagina, or to mucous membranes.
Possible Side Effects
These are some of the most common or most serious side effects of this medication. Talk with your provider about the side effects you are having and how they can be managed.
Skin Changes
The treatment area will typically cause a burning feeling and, after a few days of treatment, will become red and crusted. The area will look worse than before treatment, which will likely continue for a few weeks after treatment stops. You may have any of the following in the treated area: darkening of skin color, pain, irritation, redness, itching, scarring, rash, and skin ulcerations (blisters).
Sun Sensitivity
This medication can make your skin more sensitive to the sun, which can result in a severe sunburn or rash. Sun sensitivity can last even after you are done with chemotherapy. Avoid the sun between 10 am and 4 pm, when it is strongest. Wear sunscreen every day and reapply when you are in the sun. The best sunscreen is SPF 30 or higher and protects against both types of sunlight, UVA and UVB. Wear sunglasses, a hat, and long sleeves/pants to protect your skin, a lip balm with SPF greater than 30, and seek out shade whenever possible.
Tell your providers if you develop red, painful, or itchy skin, sunburn, skin irritation, bumps, or thick, dry skin.
Other Side Effects
The amount of medication that is absorbed into your blood is limited with topical use, but some people have a deficiency of the enzyme DPD, which is needed to break down 5-FU. Let your provider know if you have a known or family history of DPD deficiency
DPD deficiency can cause serious toxicity. If you experience diarrhea, stomach pain, fever, chills, vomiting, or sores in your mouth, call your provider right away.
Reproductive Concerns
There is a higher risk of health problems for your baby if you are pregnant, become pregnant, or get someone pregnant while on this medication. To lower the risk of birth defects, you should use birth control (contraception) to avoid pregnancy. Talk with your provider about what kind of birth control is safest for you and your partner.
If you can become pregnant, you will need to use effective birth control during treatment with this medication, even if your menstrual cycle has stopped or changed. If you can get someone pregnant, you will need to use effective birth control during treatment, even if you believe you are not producing sperm.