In general, methylcobalamin does not bring cancer back.
Mecobalamin is an endogenous coenzyme B12, mainly used to treat megaloblastic anemia and peripheral neuropathy caused by vitamin B12 deficiency. Mecobalamin is also used in combination with carbamazepine and cotrimoxazole cream to treat herpes zoster neuralgia, and there is no authoritative information to suggest that methylcobalamin can make cancer come back.
Methylcobalamin may cause adverse reactions such as rash, loss of appetite, nausea and vomiting, diarrhea, etc. Once an allergic reaction such as rash exists, stop using the drug immediately. People who are allergic to this drug are prohibited from using it; workers engaged in mercury or other compounds should not use the drug in large quantities for a long period of time. If the medication is used for more than one month without effect, it is not necessary to continue using the medication.
As a prescription drug, methylcobalamin must be used under the supervision of a doctor.