Does he take coke? Irratic then down

[Roisinraisin]

YABU: Not coke

YANBU: YES Coke

So my BIL is a medical Dr, we see him 1 to 2 times a month and his behaviour is irratic sometimes, he is super happy, so energetic, so jokey borderline flirty and loud, clumsy... othertimes he seems soooo down, his speech so quiet like he is whispering to himself, body language and demeanour slow and hesitant like his dog died and he is the shyest boy on earth. He is slim like bmi 19, I never see him have a runny nose though. You never know which jekyl or hyde you're getting each time.

Could it be coke or what?

possibly, there may also be other mental health things going on like bipolar disorder...

Definitely possible. But I'd say the quiet version is a come down day and the happy day is a coke free day. Or he's hungover.

A stimulant drug of some description.
Could he have access to those being a DR?

Yes I'm sure he has access..

Bipolar cycles in men that you get differing moods in the same month, sometimes week?

With the sheer volume of work your BIL would have put into his career and the drain his job may take on him personlly, the last thing you should suspect as the cause of his polarising moods is drugs.

The risk could be the equivalent of career suuuuuissside.

Give him time and his moods will perk up.

I think it’s a bit of a stretch to leap to cocaine just because your BIL is sometimes quiet and sometimes happy! Perhaps he has a stressful job and work stresses get too much sometimes. Or perhaps he just doesn’t always want to be social because he’s tired or has relationship/work/family issues or pressures!