Lactobacillus acidophilus is a probiotic bacterium that lives naturally in the human gut and appears in fermented foods. Commercial supplements list a specific strain, such as NCFM or LA-1, because different strains produce different effects.
Most people take it to keep their gut microbiome in good shape, especially during or after a course of antibiotics, or to ease temporary digestive upset. Certain strains also support immune function.
A standard routine involves one dose per day, often on an empty stomach or right before a meal. This timing helps more bacteria survive stomach acid. The right dose depends entirely on the strain and product used.
Mild gas or bloating can happen when you first start taking it. Anyone with a severely weakened immune system or a critical illness should check with a doctor.