A lot of household cleaners and bug sprays tend to say not to induce vomiting when ingested unless advised by poison control or something. I’m curious as to why. Is it because they will cause more damage coming up? Because you’ll dehydrate yourself?
It’s usually caustic things that will cause more damage on the way up. You should drink milk to neutralize it instead.
Source: 6th grade health class, 1977.
It also risks getting the poison or caustic into the lungs where it can do more damage, it can impede breathing if it’s something than can froth or foam, it actually causes your body to absorb more of the poison as pressure is put on the stomach to eject the contents, once started vomiting can be hard to stop and it can interfere with the ability of emergency medical personnel to treat the injury with a more effective solution such as activated charcoal.
Cleaners may be caustic or acidic as noted above. However things containing hydrocarbons are also very nasty - so bug sprays, solvent cleaners, other things that are dissolved in a hydrocarbon solvent (eg furniture polish), kerosene, gasoline, diesel, etc. These can get into the lungs, and only a very small amount aspirated can lead to a pneumonia that is quickly life threatening.