Pyrimidine analogue used for the treatment of several types of malignancies. Topical 5-FU is widely used for the treatment of actinic keratosis and warts in some countries.
Risk factors
Seborrheic dermatitis (palmar-plantar dermatitis).
Iterative long-term topical applications.
Clinical manifestations
Anaphylactic shock (4 cases reported).
Palmar-plantar dermatitis.
Contact eczema by topical application, pigmentation abnormalities, phototoxicity and photosensitization.
Diagnostic methods
Cutaneous testing: one case with intradermal test positive (anaphylactic shock).
Patch-tests and photopatch-tests with 0.5-1% 5-FU in pet.
No specific IgE found.
IgE-mediated hypersensitivity (one case of anaphylactic shock).
Probable direct cytotoxic effect of 5 FU (palmar-plantar dermatitis).


  1. Nadal C, Pujol R.M, Randazzo L, Marchello E, Alomar A, "Systemic contact dermatitis from 5-Fluorouracil", Contact. Dermatitis., 1996; 35: 124-5
  2. Milla Santos A, Sanchiz Medina F, "Anaphylactic reaction following i.v administration of 5-fluorouracil (letter)", Cancer. Treat. Rep., 1986; 70 (11): 1346
  3. Sridhar K.S, "Allergic reactions to 5-fluorouracil infusion", Cancer., 1986; 58: 862-4
  4. de Beer R, Kabakow B, "Anaphylactoid reactions associated with intravenous administration of 5-fluorouracil", N.Y. State. J. Med., 1979; 79: 1750-1

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.