OK, it can maybe trigger a panic attack if they don't realise what's happened, or in a particularly panicky person, you should try to calm them if you're not a douchebag, but they're self limiting because of the amount of cannabis. It's not like a hypertensive panic attack, the blood pressure is low. Caffeine can help to increase blood pressure & there's not much in a normal cup of tea. Sugar helps too. There's absolutely no need for benzos, at least not in 99% of cases. I've no idea why more weed helps, maybe it's the CBD or CBN or something, but these effects only occur when the rate of THC in the blood/brain/whatever is increasing at a steep rate. It either speeds up the whitey & makes them throw up, or afterwards it's calming.
You can see the blood pressure is low because they go so unnaturally pale. It's really nothing like any normal panic attack, at least not physically. It's not something that needs benzos. You can clearly see the difference between a whitey & a panic attack. If they're having a panic attack off weed, that's different.
There's clear stages to a whitey & they're usually over in minutes. It's really not something to panic over. You go pale, feel ill, start to think you're dying, throw up, start to feel better, then get something to eat/drink & recover 100%.
There's no use going off the deep end & treating it like a real drug overdose, it's nothing like, it's just a trick, they're not really dying, just tripping that they are & it's all over in under an hour. This is why it's funny, I'd never laugh at serious injuries. My friends laugh at me if I whitey, just like I laugh at them.
THC alone can create feelings of doom, it's hallucinogenic. Check this video IV pure cannabinoid experiment:
https://www.youtube.com/watch?v=T2cAFRAX3Gs
If they've had any other drugs or are prone to severe panic attacks, then it could indeed be serious, but nobody ever died from just smoking cannabis, they just feel like they're about to.
