The simple formaldehyde molecule is a highly sensitizing molecule that is the underlying cause of contact dermatitis in many patients. Exposure to formaldehyde gas at work and in the home (insulation with urea-formol foam) can lead to the development of asthma.
It is also used for sterilization, notably of dialyzers, as an antibiotic additive in grooming products (toothpaste, shampoo, soaps) and in certain medications (antihepatitis B vaccine, certain allergoids).
Anaphylactic shock is uncommon (hemodialysis and dentistry). Contact dermatitis is frequent.
Previous exposure to formaldehyde.
Differentiate from irritation syndrome (ocular, nasal, bronchial).
General: anaphylactic shock.
Cutaneous: urticaria, angioedema, contact dermatitis, polymorphous erythema, maculopapular rash on the face and in the mouth (dentistry).
- prick-tests using formaldehyde solutions at 0.1 and 1% are often positive in subjects presenting immediate reactions. Results should be read immediately (20 minutes).
- patch-tests using a formaldehyde solution at 1% are often positive in subjects with contact dermatitis (high doses are irritating and should not be used).
Specific IgE antibodies against formaldehyde can often be detected by RAST or ELISA in subjects with immediate manifestations.
IgE-mediated hypersensitivity (anaphylactic shock).
Cell-mediated hypersensitivity (contact dermatitis).
Type III: IgG antibodies against formaldehyde/serum albumin conjugates have been detected in patients exposed through the respiratory or parenteral route.
Avoid using dialysis membranes sterilized with formaldehyde in patients with previous allergic skin reactions to formaldehyde.
Perform an intradermal test with antihepatitis B vaccine in patients presenting contact dermatitis to formaldehyde (risk of generalized urticaria or eczema).