Don's Home Health Skin Actinic keratoses (a pre-cancerous skin condition)
Treatment:
Fluorouracil Topical (5-FU, Carac®, Efudex®, Fluoroplex) Cream is typically used to treat Actinic keratoses.BR> It is applied 2 times per day for 2-4 weeks.

CLINICAL PHARMACOLOGY
There is evidence that the metabolism of fluorouracil in the anabolic pathway blocks the methylation reaction of deoxyuridylic acid to thymidylic acid. In this manner, fluorouracil interferes with the synthesis of deoxyribonucleic acid (DNA) and to a lesser extent inhibits the formation of ribonucleic acid (RNA). Since DNA and RNA are essential for cell division and growth, the effect of fluorouracil may be to create a thymine deficiency that provokes unbalanced growth and death of the cell. The effects of DNA and RNA deprivation are most marked on those cells that grow more rapidly and take up fluorouracil at a more rapid rate. The contribution to efficacy or safety of individual components of the vehicle has not been established.
Source: Fluorouracil Cream RxList

How to use: kaiserpermanente.org

It is important to keep your face gently washed during treatment. You may apply Aquaphor, Vaseline, or over-the-counter Hydrocortisone ointment to the area treated after applying Efudex. Do not apply prior to Efudex application.

How should fluorouracil cream be used? | DermNetNZ.org
Fluorouracil cream is applied once or twice a day after washing with plain water. A tiny amount of the cream should be gently rubbed into all of the treatment areas with a fingertip. It is important to apply it to all the skin and not just visible lesions.

Avoid putting fluorouracil cream in the eyes; it is not normally used on eyelids. Keep it off the lips, unless specifically instructed to use it on this site. Use it with care in skin folds (such as those around the nose and lips), since it may irritate more severely in these areas.

Due to interaction with sunlight, it is best to use fluorouracil cream during the winter months. Treated skin should normally be very carefully protected from the sun; stay indoors during the middle part of the day. If the treated area is inadvertently exposed to the sun, the reaction to fluorouracil is more vigorous than normal.

Skincare Products and Efudex: If and When I Use Them | SkinCancer.net

It is important to keep your face gently washed during treatment. You may apply Aquaphor, Vaseline, or over-the-counter Hydrocortisone ointment to the area treated after applying Efudex. Do not apply prior to Efudex application. 

What to do when you're finished:
advice from bard.google.
Use a mild soap to remove it and hydrate your skin. e.g.

There are a few good mild soaps that can be used to remove fluorouracil. Some of these include:
luorouracilCetaphil Gentle Skin Cleanser
CeraVe Hydrating Facial Cleanser
La Roche-Posay Toleriane Hydrating Gentle Cleanser
Aveeno Calm + Restore Oat Gel Cleanser
Vanicream Gentle Facial Cleanser



There are a few good skin creams that can be used after fluorouracil treatment. Some of the most popular options include: