I have bleached or previously chemically dyed hair. Can I use this henna, and what should I be careful about? — Iranian natural henna, 25 g

Yes, you can use this henna on bleached or chemically treated hair, but extra caution is needed. Chemically processed hair is often more porous, which can cause the henna to absorb more intensely and unevenly, potentially leading to patchy or overly bright results, especially on lighter sections. Furthermore, if there are any residual metallic salts from certain old dyes or treatments present in your hair, henna can react with them, causing unexpected color shifts (like greenish tones) or damage.

The essential step is a thorough strand test. Take a small, inconspicuous section of your hair, prepare the henna paste as instructed, and apply it for the full intended processing time. Observe the final color after 48 hours. This test will reveal how your specific hair will react. It's generally advised to wait at least 2-4 weeks after your last chemical service before applying henna. Also, be aware that once henna coats your hair, it can be difficult to remove and may affect the outcome of future chemical coloring, so it's often considered a semi-permanent commitment.