Known safety concerns, contraindications, and risk factors.
Peptide therapy for immune regulation sits at the intersection of a plausible and growing evidence base and an unsettled regulatory environment. The information in this protocol is educational, not prescriptive. Any peptide use — particularly Thymosin Alpha-1, Thymosin Beta-4, Selank, and Khavinson bioregulators — should be initiated only under the guidance of a physician competent in peptide therapeutics, using pharmaceutical-grade product. Grey-market sourcing substantially elevates risk and is the source of most documented safety incidents. The FDA Category-2 classification affects legal access in the US; outside the US the regulatory picture varies.
Hematopoietic stem cell transplantation
Thymosin Alpha-1 is absolutely contraindicated.
Organ transplant recipients / deliberate immunosuppression
Thymosin Alpha-1 is strictly contraindicated.
Liver failure
Avoid Thymosin Alpha-1 due to potential temporary ALT elevation.
Pregnancy and breastfeeding
Generally contraindicated across the peptide class.
Children and adolescents
Not recommended unless under strict medical supervision.
Active malignancy or cancer history
Significant risk factor for peptides influencing cell proliferation (Selank, LL-37).
Hypersensitivity to peptide or excipients
Primary contraindication for any peptide.
Autoimmune disease (psoriasis, SLE)
LL-37 can act as an autoantigen and trigger flares.
HIV risk exposure
LL-37 upregulates receptors in Langerhans cells that increase susceptibility to HIV infection.
Osteoporosis or low bone density
LL-37 induces osteoblast apoptosis in vitro.