Solvents

Users say it's like being drunk with dizziness, dreaminess and fits of the giggles. And it can be difficult to think straight.
Depending on what's being inhaled, you can hallucinate. This can last for up to 45 minutes.
The hit is quite short so users tend to keep repeating the dose to keep the feeling going.

People can experience vomiting and blackouts.
There's a risk of fatal heart problems which have been known to kill users the very first time they sniff.
Squirting gas products down the throat is a particularly dangerous way of taking the drug. It can make your throat swell so you can't breathe and slows down your heart.