Known and theoretical safety concerns include: Retatrutide (and the GLP-1 receptor agonist class): Nausea, vomiting, diarrhoea, and reduced appetite are the most commonly reported side effects
The above is usually talked of in terms of 'anaemia', but it does show that there is a complicated link between B12, B6, folic acid, zinc and vitamin D levels, chronic disease (anaemia of chronic disease) and how the body 'manages' serum iron, ferritin, and transferrin iron saturation and keeps these in balance (or not, as in your case)
Side effects are usually minor, but if your ankles start to swell or you have an allergic reaction or trouble breathing, call your doctor
As well, methylation helps to produce neurotransmitters for memory, concentration, and mood