A: Not in my experience. From a pharmacology standpoint, when you apply topical hormones, they get absorbed through your skin and they avoid the first pass effect, which is what happens when you take things orally: they first pass through your liver. That interferes with the metabolism, and that is how a lot of the drug interactions happen. For example, when you swallow thyroid meds and iron at the same time, that can change the pH of your stomach and impact that absorption. But as far as the topicals, we don’t necessarily see anything that you're taking orally that should interfere with their metabolism and absorption. The things that could impact the absorption of topicals would be your body temperature, or if you wipe off the cream too quickly after application, or if you take a shower right after application. Exercising right away after application can increase absorption. Other things that may interfere are the thickness of your skin and the lipid content of your skin– your weight and body fat in the place where you're applying it may impact absorption. Furthermore, hair follicles, sweat glands, pH of your skin, blood flow, higher temperature/lower temperature could also impact your absorption, as well as your hydration and any inflammation present. Other factors include: covering up the area after application with something that can increase the penetration and absorption; doing a sauna after application, which can impact and change the variability of your topical absorption.
All these factors can play a role in the variation in absorption that you are seeing.