B-Complex shots, also called cobalamin injections, have often been used to treat people with acute anemia which results from a deficiency of this vitamin. They can help improve energy levels, and aid in weight loss.
Typically, the B vitamins are not easily absorbed by the body, but when consumed with green vegetables such as broccoli and/or spinach, the absorption rate is enhanced.

Uses of Injection of Vitamin B Complex-

• Fever
• Severe burns
• Increased metabolism
• Pregnancy
• Gastrointestinal disorders

Side effects-

• Muscle cramps
• Irregular heartbeat
• Unusual weakness or tiredness
• Swelling of the ankles or feet