Biotin works with some other B vitamins, such as folic acid, pantothenic acid (vitamin B5), and vitamin B12. However, no solid evidence indicates that people supplementing with biotin also need to take these other vitamins. Symptoms of pantothenic acid or zinc deficiency have been reported to be lessened with biotin,¹¹ though people with these deficiencies should supplement with the nutrients in which they are deficient. Researchers have speculated that biotin and alpha lipoic acid may compete with each other for absorption or uptake into cells; but little is known about the importance of these interactions in humans.¹²

There is one report of a 76-year-old woman who developed a life-threatening condition (eosinophilic pleuropericardial effusion) while taking 10 mg of biotin per day and 300 mg of pantothenic acid per day.¹³ However, it is not clear whether the vitamins caused the problem.