Which side effect is commonly associated with taking multi-vitamins?

Constipation is a commonly reported side effect associated with taking multi-vitamins, particularly those that contain iron and certain minerals. These components can slow down digestion or affect the gut flora, leading to less frequent bowel movements. Additionally, some individuals may have sensitivities to specific ingredients in the multi-vitamins that can exacerbate this issue. It is important for individuals taking multi-vitamins to be aware of this potential side effect and to maintain adequate hydration and fiber intake to help mitigate the risk of constipation.

The other options, while they may represent effects of other dietary changes or medications, are not typically linked to the use of multi-vitamins in a direct manner. For instance, fatigue could be related to various health conditions or deficiencies but is not directly a consequence of multi-vitamins. Increased appetite and weight gain are more associated with dietary changes or other medications rather than multi-vitamin supplementation.