The retinoid comparison makes GHK-Cu discontinuation appear favorable since copper peptide cessation typically produces gradual benefit decline without rebound worsening or dramatic rapid reversal
Increased Energy : One of the most common reasons people turn to B12 injections is for an energy boost
At therapeutic doses it is safe for most people, but acetaminophen metabolism uses glutathione directly, and chronic high dose use is the leading cause of acute liver failure in the United States precisely because it exhausts hepatic glutathione (PubMed PMID: 26041729)
These are typically mild to moderate and improve with gradual dose increases
However, some rare side effects of too much vitamin B12 can include: Headache Weakness Nausea Diarrhea Tingling sensations in the hands and feet Allergic reactions or skin rash (uncommon) When To Seek Medical Advice Risk of vitamin B12 deficiency: Groups at a higher risk of vitamin B12 deficiency include older adults, people who only eat plant-based foods (vegans and vegetarians), and those with certain chronic conditions (gastrointestinal disorders that can affect vitamin absorption)
However, the discontinuation rates are virtually identical