Yes, there can be side effects of B12 shots, although they are generally rare and mild. Some possible side effects include: 1. Pain and swelling at the injection site. 2. Itching, redness, or rash at the injection site. 3. Headache, dizziness, or nausea. 4. Anxiety, nervousness, or restlessness. 5. Low blood potassium levels. If you … Continue reading Are There Any Side Effects of B12 Shots?