Vitamin B12

Vitamin B12 as an injection, so it doesn't depend on how well your gut absorbs it. It isn't a peptide.

Energy, red blood cell formation, nerve health and metabolism. Absorption from food often drops with age and with some medications.

A small under-the-skin injection you give yourself at home. The prescribing provider sets the dose and schedule, and the pharmacy sends written instructions with your order. We walk you through the first one if you'd like.

If you were low, energy often improves within a few weeks. If you weren't, you may not notice much.

• Anyone with a cobalt or B12 allergy.
• The partner medical intake asks about your health history and current medications, and the provider decides whether it's a fit.