Answered by Shaykh Abdul-Rahim Reasat
Question: Assalamu Alaykum
I have observed my sisters and friends using some organic substance to thicken the eyebrows and eyelashes and help them grow. Is this permissible?
Answer: Wa ‘alaykum as-salam
Thank you for your question.
It is permissible to use Kohl (Antimony) as it benefits the eyesight and promotes the growth of the eyelashes (Abu Dawud, Tirmidhi). I would be permissible to use substances to promote the growth of eyebrows and eyelashes as long as they look feminine, and this is not done in a manner which attracts undue attention fro the opposite gender. Please refer to this answer for more details as the rulings are similar.
And Allah knows best.
[Shaykh] Abdul-Rahim Reasat