During the decade that LLLT has been investigated and used to treat human hair loss, there are no known negative side effects.
More broadly, LLLT has been applied in different ways for decades, and the broad consensus is that it is safe.
The capacity for LLLT to activate Harrel’s growth was first discovered in a survey of mice more than fifty years ago.
But if you have unusual, questionable freckles on your scalp, you should talk to your primary health care provider or dermatologist for you to be safe. And you should not use LLLT if you have active skin cancer of the scalp.
The lack of side effects and regulations makes it more attractive than finasteride for some people.