One thing I do sometimes is search for the name of 2 different supplements on Amazon and see if I can find a commercial stack where they appear together, then check for 1 star reviews of the stack that describe a negative interaction. (This works best for stacking supplements that have similar purposes, e.g. if you’re taking 2 sleep aid supplements at once, it’s plausible that they both appear in a commercial stack that someone put together.)
One thing I do sometimes is search for the name of 2 different supplements on Amazon and see if I can find a commercial stack where they appear together, then check for 1 star reviews of the stack that describe a negative interaction. (This works best for stacking supplements that have similar purposes, e.g. if you’re taking 2 sleep aid supplements at once, it’s plausible that they both appear in a commercial stack that someone put together.)