Milk of Magnesia (MoM), an over-the-counter medication used as both a saline laxative and an antacid, is traditionally dairy-free. Its primary components do not include milk-derived proteins (casein or whey) or milk sugars (lactose). The preparation is a simple mineral-based suspension, making it generally safe for individuals with a dairy allergy or lactose intolerance.
MoM uses a naturally occurring mineral to alleviate symptoms of heartburn, acid indigestion, and occasional constipation.
The Core Composition of Milk of Magnesia
The fundamental reason Milk of Magnesia (MoM) is dairy-free lies in its active ingredient: magnesium hydroxide. This compound is an inorganic substance, a white solid, and is not derived from any animal or dairy source. Magnesium hydroxide acts as an antacid by neutralizing excess stomach acid and functions as a laxative by drawing water into the intestines.
The product is created by suspending this magnesium hydroxide mineral in purified water. This combination forms a milky-white, alkaline liquid mixture. Since the active component is a mineral and the base is water, dairy ingredients are excluded from the core formulation.
Understanding the “Milk” in the Name
The name “Milk of Magnesia” is a proprietary term that often causes confusion regarding its dairy content. The word “milk” refers not to a dairy component but to the physical, visual appearance of the liquid product.
Magnesium hydroxide does not fully dissolve in water; instead, it remains as tiny, insoluble particles suspended throughout the liquid. This fine suspension of white particles gives the mixture a characteristic white, cloudy, and opaque look, similar to milk. The term was first used in 1880 by its inventor, Charles Henry Phillips, to describe this milky-textured liquid.
Checking for Dietary and Allergy Triggers in Flavorings
While the original, unflavored Milk of Magnesia is inherently dairy-free, consumers must exercise caution when selecting flavored varieties, such as cherry or mint. These flavored options require the addition of inactive ingredients to improve taste, texture, and shelf life. These additives, though typically non-dairy, can introduce other compounds relevant to specific dietary restrictions or allergies.
Common inactive ingredients in flavored versions can include sweeteners like sucrose or sorbitol, stabilizers such as xanthan gum or carboxymethyl cellulose sodium, and various flavorings and colorants. For individuals adhering to strict vegan diets, some of these flavorings or colorants might have a non-plant-based origin. Therefore, checking the inactive ingredients list on the package label for the specific brand and flavor is the most reliable step for complete assurance.