Safe ways of coloring your hair in black

Hi il sis's
Can anyone of you pls suggest the safe ways of coloring the hair in black. One of my cousins who is 45 yrs old is used to applying Garnier color naturals (black) since long (I think since 2003). Then she shifted to natural henna, she didn't like the reddish color, so she shifted to 'nice and easy root touch-up' during her 4 yrs stay in the U.S. She returned to India and again shifted to garnier color naturals (black).

But since the past 4-5 times, she is getting burning / itching sensation on the scalp on applying garnier. So, she wants to go for a safe hair colorant.

Can anyone of you pls, give expert suggestion?

Also pls, let her know, what could be the probable reasons for this burning sensation? Should she visit a dermatologist or a doctor? As of now, there are no other skin / hair related problems than this burning sensation on applying garnier.

Awaiting your expert suggestions on this health / hair related issue.

Thanks in advance.

 

My cousin is eagerly waiting for responses / suggestions from the expert ilites.

Pls respond.

 

Hmm! No responses though there are 75 views. :bonk