Do You Need a Letter of Medical Necessity for Red Light Therapy?

Short answer: most FSA/HSA-eligible red light therapy devices don't need a Letter of Medical Necessity to purchase — if it rings up clean at checkout or your manual claim gets approved, you're done. But if your plan administrator flags the purchase, denies a reimbursement claim, or your plan asks for medical documentation, a short letter from your doctor is usually the fastest way to get your money back.

If you've ever submitted a red light therapy receipt to your FSA or HSA and gotten a "needs more documentation" email back, you're not alone. It's confusing, because red light devices are widely marketed as FSA/HSA eligible — and they often are. The letter of medical necessity only enters the picture in a specific, narrower set of situations. Here's how to tell which one you're in.

What is a Letter of Medical Necessity?

A Letter of Medical Necessity, or LMN, is a short, signed statement from a licensed healthcare provider that names a specific medical condition and explains why a product or service is medically needed. It's the document that turns a "dual purpose" item — something that could be used for general wellness or for a real medical condition — into a legitimate, reimbursable medical expense in the eyes of your FSA or HSA administrator.

The IRS doesn't use the phrase "Letter of Medical Necessity" anywhere in its own publications, but the concept comes from how it defines a medical expense. IRS Publication 502 limits reimbursable medical expenses to costs for medical care, and specifically excludes anything that is "merely beneficial to general health." An LMN is the document your administrator may ask for to confirm that a purchase is a qualified medical expense under your plan's rules.

Do you need one to buy red light therapy with your FSA or HSA?

Usually, no — not at the point of purchase. Most FSA/HSA-eligible AWA devices are coded so your card is accepted automatically at checkout, the same way it would be for a heating pad or a knee brace. If your card swipes clean, you don't need to do anything else. Save your itemized receipt in case your plan asks for it later, but there's no letter required up front.

Where things get more complicated is reimbursement claims — meaning you paid out of pocket and are now asking your FSA or HSA to pay you back. Some plan administrators automatically approve red light therapy as a general wellness device; others consider it dual-purpose and want to see documentation from a provider before they release funds. You usually only find out which camp your plan falls into after a claim gets kicked back.

When does a red light therapy purchase actually need an LMN?

An LMN becomes useful in a few specific situations: your reimbursement claim was denied or flagged as "needs more information," your plan document specifically lists light therapy devices as requiring extra substantiation, you're using a Limited Purpose FSA or a Dependent Care FSA account that has stricter eligibility rules, or you simply want a stronger paper trail in case of an IRS audit down the road.

It also matters what the letter says. A letter is easier to defend when it comes from your provider and reflects their own professional judgment about your situation, rather than a general goal like "wellness." Your provider decides what to write, and we can't tell you what a letter should say for your health.

What should a red light therapy LMN include?

A useful LMN is short and specific. At minimum, it typically includes the patient's name, the provider's own statement of medical need, the recommended device type, frequency of use and expected duration as the provider sees fit, and the provider's signature, license information, and the date. A vague note is weaker than a specific one. Your provider decides what goes in the letter.

Red light therapy is an active area of research. You can browse sources in our Learning Center to share with your provider. Whether to write a letter is your doctor's call, not something a store can promise on your behalf.

How do you actually get one from your doctor?

Ask directly. Most people are surprised at how simple this conversation is — providers write LMNs for dual-purpose items regularly, for everything from air purifiers to massage devices. Mention that you're asking for FSA/HSA purposes, and offer to bring in the product page or spec sheet so they can reference it in the letter. Many providers will draft one during a normal visit at no extra cost; some charge a small fee for paperwork done outside an appointment. If your provider isn't familiar with red light therapy, a one-page summary of the device (which AWA includes with every FSA/HSA-eligible product) can help them write a more specific letter.

What happens if your claim gets denied without one?

Most FSA and HSA administrators will tell you exactly why a claim was denied and what would fix it. If the reason is "dual-purpose item, documentation required," that's your cue to get an LMN and resubmit — most plans allow you to appeal or resubmit a denied claim rather than losing the funds outright. If you're not sure why a claim was denied, call your plan administrator before assuming the purchase isn't eligible at all; it may just need the extra paperwork, not a refund back to your bank account.

Frequently asked questions

Does every FSA/HSA purchase of red light therapy need a Letter of Medical Necessity?

No. Most card purchases of FSA/HSA-eligible AWA devices go through without any extra documentation. An LMN is a backup tool for reimbursement claims that get flagged or denied.

How long is a Letter of Medical Necessity valid?

It varies by plan, but many administrators consider an LMN valid for one year or for the duration stated in the letter itself. If you plan to keep using the device regularly, ask your provider to note that in the letter.

Can a nurse practitioner or physical therapist write an LMN, or does it have to be a physician?

Most plans accept a letter from any licensed healthcare provider who provides medical care, including nurse practitioners, physician assistants, physical therapists, and chiropractors, depending on your state's scope-of-practice rules. Check with your plan administrator if you're unsure.

Does AWA provide Letters of Medical Necessity?

No — an LMN has to come from your own licensed healthcare provider, since it's their professional judgment about your health. AWA can provide product information and specs to help your provider write a more detailed letter, but we can't write or sign the letter itself.

What if my FSA plan is a Limited Purpose FSA?

A Limited Purpose FSA (LPFSA) generally only covers dental and vision expenses unless you're also contributing to an HSA, so a general red light therapy device usually won't qualify under an LPFSA no matter what documentation you provide. Check your plan's specific rules before buying.

Is it worth getting an LMN just in case?

If your plan asks for documentation, an LMN costs you little more than a conversation with your provider and gives you a stronger claim if anything is ever questioned. If you're using it for general wellness, an LMN likely won't change your eligibility either way.

Whatever situation you're in, the goal is the same: get the paperwork that matches how you're actually using the device. That's usually enough to keep your pre-tax dollars working the way they're supposed to. For the full rules on FSA/HSA eligibility, deadlines, and which AWA devices qualify, see our FSA/HSA eligibility guide, or browse the full FSA/HSA-eligible collection.

This article is for general education and is not medical advice. Red light therapy devices are intended for general wellness and are not intended to diagnose, treat, cure, or prevent any disease. Always check with a qualified healthcare provider before starting a new therapy.