Reported effects include: Local discomfort at the injection site
Is B12 absorbed better via IV or IM injection
DNA was not isolated from the first two samples collected in the LD/LD-V group, and the first sample collected in each of the other respective groups, due to the use of saline to flush the cecum (after weighing) during early collection (therefore, n = 25 cecal samples)
[1] For this reason, it might be advised to remain in the clinic for 10-15 minutes after the first injection to ensure you dont react
Worldwide trends in scientific publications on association of gut microbiota with obesity (in Eng)
That said, side effects can occur: Common side effects (mild and transient) Injection site reactions: Redness, mild swelling, or tenderness at injection sites