The Cytochrome P450 A series of enzymes is involved in N-demethylation of various tryptamines. Inhibitors of these enzymes can reduce the ability of your body to metabolize certain tryptamine compounds such as ergot alkaloid used in migraine therapy. Some are also involved in the metabolism of harmaloids although the D kinds are more involved.

Although drinking grapefruit juice with shrooms is most likely harmless purposely trying to inhibit enzymes that are meant to break down drugs and toxins is dangerous for your liver and brain if not done correctly. Strong cytrochrome p450 inhibitors is definitely not recommended. Grapefruit juice again is harmless in this regard.