Henna, eyebrow, and eyelash dye products contain ingredients that may cause skin irritation or allergic reactions in some people. 

Henna powder contains PPD, an aromatic amine used in all types of eyebrow and hair dyes, which can cause an allergic reaction. Recommendation: Always test with "black or dark brown" shades, as they contain the highest percentage of PPD.

Always perform a patch test before using henna, eyebrow, or eyelash dye products on your clients. Allergy patch testing is important, even though henna is a natural product. Perform the patch test on the wrist or behind the ears 24to 48 hours before the treatment is performed. 

Performing a Patch Test

Wash your hands and then put on gloves.

Clean and rinse a small area of the client’s skin with soap and water, for example behind the ear or on the inner side of the forearm.

Mix the products according to the preparation instructions. Apply the mixture to a small area behind the client’s ear or on the inside of the forearm and let it set for 2 minutes.

Remove the mixture with a cotton ball moistened with water. Advise your client to return in 24 to 48 hours. If no skin irritation or inflammation is visible, it is generally assumed that there is no hypersensitivity to the product and that the treatment can be performed. 

Allergic reaction

If a reaction occurs during the patch test, such as severe stinging, irritation, a rash, or a burning sensation on the skin, rinse the skin immediately and discontinue use of the product.

If the client experiences (mild) respiratory irritation, they should seek immediate medical attention and consult a doctor.

If itching, redness, or spots on the skin occur in the days following the patch test, or if there is swelling of the eyes, face, or skin, it is recommended that the client consult a doctor and not undergo the treatment.