Misconceptions About Allergic Contact Dermatitis (ACD)
| Misconceptions | In fact |
|---|---|
| Rash should quickly follow contact. | Rash is usually delayed 1—2 d and may not appear for a week after contact. |
| Allergy develops mainly to new substances. | Allergy can develop at any time, to any product, even after years of contact. |
| Allergy is dose dependent. | Allergies are not necessarily dose dependent. |
| If a consumer changes exposure to a product and the rash doesn't clear, the product is not the cause. | Many products contain the same or cross-reacting antigens, and product composition can change without notification. |
| Contact allergy occurs only at the site of exposure to the antigen. | Although the dermatitis is often most severe at the site of exposure, dermatitis can become generalized or can be spread to distant sites (e.g., nail polish transferred to eyelids). |
| Negative scratch/prick testing or negative radioallergosorbent testing (RAST) as carried out by allergists rules out ACD. | Only patch testing is diagnostic. |
| Expensive products are less likely to be allergenic. | Cost of products does not determine its allergic properties. |