Rare side effects of B12 shots (require medical attention) Serious reactions to B-12 shots are uncommon, but its important to be aware of them: Allergic reaction, including rash, hives, dizziness, or trouble breathing Significant swelling, pain, or warmth that worsens at the injection site Palpitations or chest discomfort Signs of drug interactions, especially if you take multiple prescription medications If you experience symptoms that feel intense, progressive, or unusual, you should contact your provider right away

Symptoms of B12 deficiency include: Low energy and fatigue Digestive problems Depression and moodiness Insomnia Brain fog and memory loss Anemia Reduced immune system function Tingling or numbness in the extremities Swollen tongue Loss of vision or hearing Jaundice Kidney disease Pale skin Poor circulation in the extremities If you are over age 50 and are experiencing one or more of the above symptoms, boosting your intake of B12 cannot hurt, and it may provide a safe and inexpensive solution while preventing a wrong diagnosis
The evidence is clear: for most patients, high-dose oral supplements are as effective as injections
Efficacy of sublingual apomorphine (APL-130277) for the treatment of OFF episodes in patients with Parkinson's disease (P2.335)