Is lactose intolerance contagious?

    Written by:
    Natalka Roshak

    Fact-checked

    by:

    Shyam Jayaraman, Louie Neri
    Last Updated: May 16, 2025

    Lactose intolerance is not contagious; however, it can be heritable. Primary lactose intolerance is associated with the absence of the lactase enzyme in adulthood, whereas congenital lactose intolerance is a rare autosomal-recessive disorder.

    No, lactose intolerance is not contagious.

    However, primary lactose intolerance, which results from the normal low-to-absent production of lactase enzyme in adulthood, is heritable. In other words, if neither of your parents has the mutation which lets their bodies produce lactase into adulthood, you aren’t likely to, either. Congenital lactose intolerance (the inability to digest lactose from birth) is also heritable, although extremely rare; it’s an autosomal-recessive disorder resulting from a different mutation in the LCT gene (the gene that allows the body to produce lactase).[1]