Hair Dye Allergy: PPD, Patch Tests and the Kala Mehndi Danger
Hair dye allergy is usually caused by PPD, found in most dark dyes and in black henna. Learn the signs, how to patch test, and why kala mehndi is risky.
Condition guide
Contact dermatitis and skin allergy
Also known as Allergic contact dermatitis, Irritant dermatitis, Hair dye allergy, Skincare reaction, Skin allergy.
In short
Contact dermatitis is a rash caused by something that touches the skin. Irritant reactions sting, burn or redden the skin soon after contact, often from harsh cleansers or too many active products, while allergic reactions are itchy rashes that can appear a day or two later, from triggers such as hair dye, nickel, fragrance or rubber. Stopping the trigger usually lets the skin settle, and a dermatologist can confirm an allergy with a patch test.
Typical signs
- An itchy, red or darker rash where a product or object touched the skin
- Stinging or burning soon after applying a skincare product
- Itching, swelling or blisters on the scalp, ears, eyelids or neck after hair dye
- A rash under a watch strap, earrings or belt buckle
- Dry, cracked skin on the hands from work exposures
When to see a dermatologist
- A reaction does not settle within a few days of stopping the product
- Your scalp, face or eyelids are swollen, blistered or oozing
- A rash keeps coming back in the same places
- You have reacted to hair dye, mehndi or a temporary tattoo
- Work exposures such as cement, rubber gloves or chemicals seem to trigger your rash
- Get emergency help at once if there is swelling of the lips, tongue or throat or difficulty breathing
Signs vary from person to person and several skin conditions look alike. Only an examination can confirm a diagnosis.
Read the guides
Full, referenced articles on contact dermatitis and skin allergy written for Indian skin, with answers to common questions.
Patch Test for Skin Allergy: What to Expect
A patch test finds the cause of allergic contact dermatitis. Allergen patches stay on your back for two days, with readings over a week. How to prepare.
Sensitive Skin: Why Skincare Products Sting, Burn or Cause Rash
Stinging soon after skincare usually means an irritated skin barrier; an itchy rash a day or two later may be allergy. Stop the product and simplify.
Basic Skincare Routine by Skin Type: A Dermatologist's Guide
A good routine needs just three steps: a gentle cleanser, a moisturiser suited to your skin type and daily sunscreen. Add one active only for a clear concern.
Rosacea and Sensitive Skin: Symptoms, Triggers and Care
Rosacea causes flushing, redness, bumps and stinging, and is often missed on brown skin. Gentle care, sun protection and treatment can keep it calm.
Worried about contact dermatitis and skin allergy?
Book an online consultation with Dr. Maria Ansari for an assessment and a written care plan made for you.
This page is a short summary for general education and does not replace a consultation with a qualified dermatologist. Do not start, stop or change any medicine based on this page. Read the full medical disclaimer.