From the Research
Community pharmacists should advise customers using hair coloring dyes to always perform a patch test 48 hours before full application, even with previously used products, to check for allergic reactions. This is based on the study by 1, which found that 87% of patients with allergic contact dermatitis due to para-phenylenediamine had a positive patch test reaction to at least one hair dye product, highlighting the importance of sensitivity testing.
When advising customers, pharmacists should recommend:
- Carefully reading and following all manufacturer instructions
- Wearing protective gloves during application
- Maintaining proper ventilation in the application area
- Never exceeding the recommended processing time
- Thoroughly rinsing hair after coloring
- Considering hypoallergenic or ammonia-free formulations for those with sensitive skin
- Being aware that permanent dyes containing para-phenylenediamine (PPD) pose higher allergy risks than semi-permanent or temporary options
Pharmacists should also caution against using hair dye on:
- Damaged or irritated scalps
- During pregnancy (especially first trimester)
- When experiencing respiratory conditions that could be aggravated by chemical fumes They should explain that allergic reactions can range from mild irritation to severe symptoms requiring medical attention, and that sensitivity can develop even after years of uneventful use. Additionally, customers should be advised to wait at least two weeks between coloring treatments to minimize hair damage and scalp irritation, as the chemicals in hair dyes can disrupt the hair's protein structure and natural protective barrier, as noted in the study by 2.
It's also important to note that some hair dye products may contain other allergens, such as m-aminophenol and toluene-2,5-diamine sulfate, as found in the study by 1, and that even products labeled as "hypoallergenic" or "non-allergenic" can still cause reactions. Therefore, pharmacists should emphasize the importance of patch testing and careful product selection to minimize the risk of adverse reactions.