This is the answer I got: No, injecting B12 for pernicious anemia does not typically cause thick blood
The purpose is maintaining optimal levels while the body completes the deeper structural repair that takes longest
[17] While it technically refers to anemia caused specifically by autoimmune deficiency of intrinsic factor, it is commonly used to refer to B 12 -deficient anemia as a whole, regardless of cause
So, talk to your doctor if you take any of these
Does a Vitamin B12 Injection Hurt
Recommended Timing Protocols Morning Fasted Protocol (Most Common): Timing: Upon waking, before any food or caloric beverages Fasting Window: At least 8-10 hours fasted from overnight sleep Post-Injection: Wait 30-60 minutes before eating breakfast Activity: Light fasted cardio or morning routine before first meal may enhance fat mobilization Advantages: Convenient, consistent daily routine, maximizes overnight fasted state Pre-Exercise Protocol: Timing: 30-45 minutes before fasted cardio or training session Fasting Window: At least 4-6 hours since last meal Rationale: Exercise during fasted state with elevated free fatty acids may enhance fat oxidation Considerations: Not suitable for high-intensity training