How you feel—and how long you feel that way—really comes down to the current state of your gut health and how your body processes the different probiotic strains. According to Shah, everyone metabolizes probiotics differently, so there’s really no definitive time frame for everyone.
As a general rule, initial unpleasant side effects typically go away within the first two weeks, when your gut microbiome starts to reach its new state of balance. Many people start experiencing gut support benefits as soon as two days after taking probiotics, but it really depends on how imbalanced your gut is to start and which strains you’re taking.*
If you don’t see unpleasant side effects start to diminish in the first couple of weeks, it’s a good idea to check in with your doctor and make sure there isn’t something else going on underneath the surface. For example, if you have small intestinal bacterial overgrowth (SIBO) or irritable bowel syndrome (IBS), the side effects may be more intense and long-lasting.
As for the fringe benefits—like less bloating and more regular elimination—those should stick around for the long haul.*