There is some evidence that suggests probiotics may contribute to brain fog. In one study, people who took probiotics reported feeling more mentally cloudy and sluggish than those who didn’t take them. However, the study was small and more research is needed to determine if this is actually a problem.
If you’re experiencing brain fog after taking probiotics, stop taking them and see if your symptoms improve. If they do, you may want to consider finding a different type of probiotic supplement or consult with a healthcare professional about other ways to improve gut health.