I posted an article on that topic on my blog in February. I pasted in the pertinent paragraphs below.
Using Your HSA or FSA To Acquire Medical Preps
A bit of sleuthing landed me on a helpful little page.
https://arcus-www.amazon.com/FSA-FAQ/b?ie=UTF8&node=17900051011
If you’ve got questions about using your FSA/HSA with Amazon, that page will probably have some answers. What it also had was a helpful link to FSA/HSA eligible products. (However, that page/link does not include medications, and least not that I could find. Typing "FSA HSA approved products" into the search bar will bring up medications as well.) And I was amazed at the wide variety of products deemed eligible.
Not only can you get your basic wound care supplies, tapes, dressings, orthopedics, and such, but you can also get toilet bowl liners, disposable bathing wipes, and incontinence underwear. And insulin syringes. (Other syringes with needles can be a little difficult to acquire, but insulin syringes are easy.) Israeli bandages, SAM splints, and QuikClot. “Emergency Wound Closures”, a couple of different brands, which tout the strength of sutures without the pain. They run about $35 each. The Scherber Premium IFAK Kit actually looked respectable—not just full of band-aids like most of them. And as I scrolled through I found a couple of others that looked pretty good.
The most pertinent information from Amazon’s website:
Q: What items are FSA or HSA eligible on Amazon?
Not all healthcare products on Amazon are FSA or HSA eligible. A list of FSA or HSA eligible products can be found
here. Eligible products also display the label "FSA or HSA Eligible" on the product page. Your FSA or HSA card can pay for the product tax and shipping. If you have ineligible items in your cart or choose to have your eligible items gift-wrapped, you can choose to add another payment method and Amazon will charge the correct amount to each card or payment method.
Q: What if I have trouble registering my HSA card?
Certain HSA cards cannot be registered as FSA/HSA cards with Amazon, but can still be used if registered as credit cards. If you register your HSA card as a credit card, you’ll be responsible for ensuring the card is used only for eligible products. HSA cards registered as a credit card do not automatically restrict the types of products you can purchase with the card. Purchasing ineligible products or services with the card may require you to report them and pay additional taxes. Contact your plan administrator or employer for more information.
As you shop, remember that you may be able to get the same items cheaper without using your FSA/HSA. Also, make sure that the products you are purchasing have the FSA/HSA designation on them to avoid hassles.