The most common warheads identified from documents were α,β-unsaturated carbonyl compounds, particularly amides, which are primarily selective for the thiol moieties of cysteine residues in proteins. Aldehydes, sulfonamides and unsaturated sulfones, α-haloacetamides, and nitriles are less common but have received significant interest from scientists, with aldehydes and nitriles being incorporated into US FDA-approved medicines. α,β-Unsaturated amides are less reactive than earlier warheads used for antitumor agents such as β-haloamines but reactive enough to form stable adducts with thiols and to form them selectively. The prevalence of amines in drug intermediates and the availability of amide-forming reactions allows α,β-unsaturated amides to be placed where neededthey can be treated as an inhibitor module in drug design.