Earlier this yr, the 53-year-old shared an image on Instagram of bald patches that had appeared in his beard.

He captioned the picture: “So that is what my beard grows like now on account of what I believe might be alopecia.

“Basically I get a bit of triangle of stubble round my mouth and a few extra on the sides."

This week, he shared an update: "Oh, jeez. It seems just like the alopecia has migrated as much as my eyebrow."

While he noted "you are not all ready" to listen to the development of his hair loss, he wrote: "I would like individuals to acclimatise to the brand new partially depilated me."

Theroux quipped that he didn't want to "freak everybody out by immediately showing in public like a half-plucked elephant fowl with no forewarning".

While the journalist says his hair loss is "out of [his] arms at this level", there is a bit of him that wants to take back control.

"I've began taking vitamin D and one thing referred to as biotin," Theroux admitted.

An updated review for 2023 on alopecia is published in the Journal of Cutaneous Medicine and Surgery.

Researchers from the University of Toronto, Canada, noted that a vitamin D deficiency is associated with the onset of alopecia areata.

However, while the data supports an association between lower levels of vitamin D and alopecia, "there's a lack of knowledge evaluating the advantage of supplementation".

Doctor Warren Heymann, on behalf of the American Academy of Dermatology Association (AAD), shared his expertise on biotin and hair loss.

"There is barely restricted proof that biotin supplementation offers a profit for hair progress," said Dr Heymann.

"To date, there aren't any scientific trials supporting claims that biotin supplementation improves hair progress or high quality."

An alopecia diagnosis might be followed by a "wait-and-see" approach, the AAD states.

"Your hair might regrow by itself, making therapy pointless," the AAD explains.

If therapy is prescribed, choices embody injections of corticosteroids, utility of minoxidil, and anthralin.