[swe02]

Isopropanol is relatively safe to drink in small amounts (single digit mL). It's only about 2x stronger than ethanol, and your liver metabolizes it to acetone, which is safe.

Denatured alcohol contains methanol, which is way more dangerous since you metabolise it to formaldehyde.

Source: I unknowingly got drunk on IPA fumes before work one time and wrote some really bad code

[dreamcompiler]

Methanol is indeed quite toxic but it is not the only denaturant. There are many others [0]. When methanol is used as a denaturant, special labeling is required [1]. Most of the denatured ethyl alcohol I've seen in pharmacies in recent years has not contained methanol but merely bittering agents, because methanol is so dangerous.

[0] https://www.govinfo.gov/content/pkg/CFR-2003-title27-vol1/xm...

[1] https://www.federalregister.gov/d/2016-20712/p-284