A method for determining a lipid imbalance in a subject is provided. The method includes providing one or more tape strips comprising a skin surface sample obtained from the subject； extracting epidermal lipids； detecting a composition of lipids present in the extracted sample； and comparing the composition of lipids to a control. A difference in the composition of lipids as compared to the control identifies the lipid imbalance in the subject. A method of augmenting a lipid deficiency in skin of a subject, for example to treat or inhibit infection, prevent water loss, improve hydration and restore barrier is also provided. The method includes identifying a deficiency in one or more lipids in a skin sample obtained from the subject； formulating a topical therapeutic composition that contains the one or more lipids, a similar lipid, or a subset thereof； and providing the composition to the subject. Topical formulations for augmenting a lipid deficiency in the skin of a subject are also disclosed.
