—even a single suck, according to Mālik and most of the scholars of Medina—renders marriage unlawful. Whatever nursing occurs after the child is two years old establishes no prohibition. Likewise, if the child is weaned before completing two years and now relies on solid food, any suckling that follows—though still within the two-year span—carries no legal effect.

Administering milk as an oral drench (wujūr) or as nasal drops (saʿūṭ) also creates the prohibition, provided the milk reaches the stomach during those first two years. By contrast, anything conveyed to the stomach without passing through the throat—such as a milk enema and the like—does not establish any prohibition.

When milk is mixed with another substance, the ruling follows whichever element predominates.

If an elderly woman—or a woman who has never borne a child, yet is of an age where intercourse with her would normally be lawful—produces milk and someone suckles from her, that person becomes her child: the prohibition generated by that milk applies between them. Should the lactating female be a young girl not yet of marital age, no prohibition arises from her milk. The same applies were a man himself to lactate: no breastfeeding relationship would be created at all.

Suckling from a deceased woman is forbidden.