The cosmetic industry convention, confirmed by Paulas Choices peptide guidance and consistent across published formulation literature, is that meaningful concentrations in topical products run from approximately 0.01% to 2%, with most well-regarded serums sitting in the 0.11% range
From there, the dose can continue increasing to 10 mg, 12.5 mg, and ultimately 15 mg if needed and tolerated
Am J Clin Nutr 102(1):115122 Demay MB, Pittas AG, Bikle DD, Diab DL, Kiely ME, Lazaretti-Castro M et al (2024) Vitamin D for the prevention of disease: an endocrine society clinical practice guideline
The right choice depends on your goals, your health status, and how fast you need results
73 Of major concern are potentially severe complications (septicaemia, infective endocarditis and transmission of blood-borne infections) of IV administration of GSH by people with no health qualifications
Acetabular labral tears