The industrial CDMOs (Bachem, AmbioPharm, CordenPharma, and PolyPeptide Group) are not online storefronts
People with digestive or absorption issues : As mentioned, conditions like Crohns disease, IBS, or celiac disease can prevent proper absorption of B12 making injections the best option for getting enough of the nutrient
Medication injected into lumpy tissue may not absorb consistently, which can lead to unpredictable blood sugar levels, especially for patients who also take insulin along with GLP-1
The drugs side effect profile, particularly gastrointestinal disturbances such as nausea, vomiting, and diarrhea, can be severe for some patients
2001 Dec;79(12):3104-12
Youve had a gastric bypass or GI disorders (like Crohns or IBS), which reduce nutrient absorption