How does this medication work? What will it do for me?

Fluorouracil - salicylic acid is a combination of two medications. Together they are used to reduce the growth of skin lesions called actinic keratosis on the face, forehead, and balding scalp. These lesions are caused by sun damage to the skin. If not treated, they may become cancerous.

Fluorouracil belongs to the class of medications antineoplastics. It works by interfering with cell division and growth to slow down the growth of cells. It is most active in cells that are growing quickly, such as skin cells affected by actinic keratosis. Salicylic acid is a keratolytic: it breaks down the outer layer of the skin to allow fluorouracil to be absorbed more effectively.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Each 1 mL of clear, colourless to slightly orange-white solution contains 0.5% fluorouracil and 10% salicylic acid. Nonmedicinal ingredients: dimethyl sulfoxide, ethanol, ethyl acetate, pyroxyline, poly(butyl methacrylate, methyl methacrylate).

How should I use this medication?

The usual adult dose of fluorouracil - salicylic acid is 1 application of the solution to the lesions, once daily. Several lesions may be treated at a time, but the area being treated should not be larger than 25 cm² (5 cm × 5 cm). A total of 10 lesions may be treated at a time.

Fluorouracil - salicylic acid should only come into contact with the lesion and a very small area of healthy skin surrounding the lesion.

Clean the affected area with warm water and wait until the skin has completely dried before applying the solution.

This medication comes in a bottle with a brush applicator attached to the cap. Wipe the brush on the neck of the bottle before applying it to the affected area. After applying the solution to the lesion, let the solution dry on the skin, uncovered. A white film will form over the affected area. This improves the absorption of the medication into the lesion and protects the lesion from dirt and debris. Do not cover the treatment area with any type of dressing. Before applying the next dose, peel the film off the lesion to expose it to the next dose of medication. Warm water may also help remove the film.

Do not allow this medication to come in contact with the eyes, the inside of the nose or mouth, or the genitals. Close the lid of the bottle tightly after using to prevent it from drying out. Do not use this medication if it dries out or forms any crystals.

This medication usually starts to work within 6 weeks. Continue to use the medication for up to 12 weeks or until the lesions have completely cleared up. It may take up to 8 weeks after stopping the medication for the lesions to completely heal.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to use this medication exactly as prescribed by your doctor.

If you miss a dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children. This medication is flammable. Keep it away from fire or flames. If there is any medication left in the bottle 3 months after opening it, safely discard the remaining medication.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take this medication if you:

  • are allergic to fluorouracil, salicylic acid, or any ingredients of the medication
  • are allergic to capecitabine
  • are allergic to salicylates
  • have reduced kidney function
  • are pregnant
  • are breast-feeding
  • have a condition known as dihydropyrimidine dehydrogenase (DPD) deficiency
  • are taking medications that interfere with DPD

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • dry eyes, eye itching, or increased tearing
  • headache
  • mild-to-moderate irritation where solution is applied (e.g., skin redness, inflammation, burning, pain, itch)
  • skin discoloration
  • skin peeling

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • severe skin irritation (e.g., bleeding, scab, redness, swelling)
  • stomach-flu-like symptoms (e.g., diarrhea, nausea, vomiting)

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • symptoms of high blood levels of fluorouracil (e.g., stomach pain, nausea, vomiting, diarrhea, unusual bleeding or bruising, black stools)
  • symptoms of high blood levels of salicylic acid (e.g., ringing in the ears, breathing fast, hast heartbeat, confusion, tiredness)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Diabetes: If you have diabetes, you may not notice severe reactions to this medication, particularly if you are applying this medication to an area of skin that you cannot see. Your doctor should closely monitor the progress of your treatment to avoid severe skin reactions.

Skin sensitivity: The area that is treated with this medication will be more sensitive to exposure to the sun. An exaggerated sunburn reaction may occur. Avoid exposure to excessive sunlight, including sunlamps and tanning beds, and use sunblock with minimum SPF 15. It is normal to experience some redness and irritation in the areas where this medication has been applied.

Staining: This solution may cause permanent staining to clothing, fabric, or acrylics, such as bathtubs. Avoid contact with these until the solution has dried.

Pregnancy: Although this medication is applied to the skin and is not expected to be absorbed into the body, other forms of fluorouracil cause harm to the developing baby when used during pregnancy. To avoid exposing the developing baby to this medication, it should not be used during pregnancy. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if fluorouracil - salicylic acid passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Breast-feeding is not recommended while using this medication.

Children: The safety and effectiveness of using this medication have not been established for children.

What other drugs could interact with this medication?

There may be an interaction between fluorouracil - salicylic acid and any of the following:

  • methotrexate
  • other skin products that cause irritation or drying (e.g., cleansers, alcohol-containing cosmetics)
  • phenytoin
  • sulfonylureas (e.g., glyburide, gliclazide)

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

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