How long you need to stop taking B vitamins depends mainly on the disease suffered and the severity of the disease. There are many B vitamins, the common B1, B6, B12, B2, folic acid, while niacin, pantothenic acid, etc. all belong to the B vitamins. Deficiencies of different B vitamins can cause different diseases, with different degrees of severity of the disease and different duration of the drugs taken. For example, the common B2 deficiency can cause stomatitis, mouth ulcers, seborrheic dermatitis, etc. Generally mild cases may be relieved by food supplementation, and most severe cases can be cured by taking oral vitamin B2 for about 1-2 weeks, as recommended. In the case of vitamin B12 deficiency, which can cause megaloblastic anemia, it usually takes 3-6 months of vitamin B12 or even longer to recover. For exactly how long you should stop taking the drug, you must consult a professional doctor and decide on the course of treatment under the guidance of your doctor.