The first tesamorelin human trials (Phase 1) began in the early 2000s, with Phase 3 trial dates spanning 2005-2008 (Study LIPO-010 Phase 3 completed 2008), leading to the November 2010 approval
Folic Acid, vitamin B9 is not a substitute for methylcobalamin, vitamin B12 deficiency, although it may improve vitamin B12 megaloblastic anemia
It can be harder to absorb as you age, and those on vegan diets may find it trickier to get enough too

Warning signs that need medical attention Seek medical evaluation within 24 to 48 hours if you experience: Redness that continues expanding beyond 48 hours after injection Redness diameter exceeding 10 centimeters Increasing pain (not decreasing) after 48 hours Warmth and hardness accompanied by fever above 100.4 F (38 C) Pus, drainage, or fluid oozing from the injection site Red streaks extending outward from the injection site (sign of lymphangitis) Reaction that has not shown any improvement after 7 days Seek emergency medical care immediately if you experience: Hives or rash spreading beyond the injection site to other body areas Swelling of the face, lips, tongue, or throat Difficulty breathing, wheezing, or shortness of breath Dizziness, lightheadedness, or feeling faint Rapid heartbeat Severe abdominal pain These emergency symptoms suggest a systemic allergic reaction (anaphylaxis), which is rare but documented with tirzepatide