What precautions should I take if I have a sensitive scalp or have recently used chemical colour treatments?

Because this product relies on plant powders rather than synthetic dyes, many people with reactive scalps tolerate it better than oxidative systems. However, natural does not mean risk-free: individual allergies to specific herbs (lawsonia, indigo, cassia, etc.) can occur. If you have a known history of contact dermatitis or a very reactive scalp, do a patch test 48 hours before full application — dab a small amount of prepared paste behind the ear or on the inner forearm and watch for redness, itching, or swelling. If you have recently used permanent colour, bleach, or a chemical perm, wait at least two weeks, preferably three to four, before applying henna. The mineral build-up from oxidative dyes can interact unpredictably with plant pigments, sometimes producing greenish or muddy tones. Conversely, if you plan to return to chemical colour after henna, inform your colourist; the herbal coating can resist or alter the uptake of oxidative dyes, and a clarifying or chelating pre-treatment may be needed. When in doubt, consult a dermatologist or trichologist, especially if you are pregnant, breastfeeding, or managing a chronic scalp condition.