vit b 100 complex side effects
B 100 Complex Side Effects. Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. When taken as directed, multivitamins are not expected to cause serious side effects.Less serious side effects may include: 1  upset stomach; 2  headache; or.et emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. When taken as directed, multivitamins are not expected to cause serious side effects. Less serious side effects may include: 1  upset stomach;