OTC Topical Pain Relievers: Creams, Gels, and Patches Safety Guide

Every year, millions of people reach for a cream, gel, or patch to ease a sore back, achy knee, or stiff shoulder. These over-the-counter topical pain relievers are easy to use, don’t require a prescription, and seem harmless-after all, they’re just rubbed on the skin. But what you don’t see on the label could be putting you at risk. Not all OTC pain relievers are created equal. Some can cause serious burns. Others contain illegal levels of numbing agents that can affect your heart. And many people use them wrong-without knowing the dangers.

What’s Actually in Your Pain Relief Product?

OTC topical pain relievers work in different ways, and each active ingredient carries its own set of risks and benefits. The most common ones you’ll find on shelves are menthol, methyl salicylate, capsaicin, and lidocaine.

Menthol is the cooling sensation you feel in products like Aspercreme Heat Pain Relieving Gel. It contains 10% menthol, which tricks your nerves into feeling cold instead of pain. But here’s the catch: Health Canada’s 2017 safety review found a direct link between menthol-containing products and rare, but serious, skin burns. These aren’t mild redness or irritation-they’re deep burns that can take weeks to heal. The agency now requires warning labels on all menthol products sold in Canada, but many products sold online or in small stores still don’t carry them.

Methyl salicylate, often found in Bengay or Icy Hot, is related to aspirin. It works by reducing inflammation at the site of pain. Unlike menthol, there’s no documented case of serious burns from methyl salicylate alone. But if you’re allergic to aspirin or take blood thinners like warfarin, this ingredient can increase your risk of bleeding. Even though it’s applied topically, your body still absorbs some of it.

Capsaicin, derived from chili peppers, works by depleting substance P-a chemical that sends pain signals to your brain. OTC versions contain between 0.025% and 0.1% capsaicin. It’s effective for osteoarthritis and nerve pain, but it takes time. You won’t feel relief right away. It can take up to seven days of applying it 3-4 times daily before you notice a difference. And when you first use it, your skin will burn. That’s normal. But if you touch your eyes afterward? That’s a medical emergency. Always wear gloves or use a roll-on applicator. Never apply capsaicin to broken skin.

Lidocaine is a local anesthetic. In prescription strength, it’s used for procedures. In OTC products, federal law limits it to 4%. But here’s the problem: the FDA found products on the market with up to 20% lidocaine. These are sold online under names like “DermaRoller Store” and “Bella’s Beauty Supply,” often marketed for use before or after laser treatments, tattoos, or microdermabrasion. That’s dangerous. When applied to freshly abraded skin during cosmetic procedures, high concentrations of lidocaine can be absorbed quickly and cause seizures, irregular heartbeat, or even stopped breathing. In July 2023, the FDA issued a public warning naming six companies selling these illegal products. They’re still out there.

When Topical Pain Relievers Are Safe-and When They’re Not

For most people, topical pain relievers are a safer choice than swallowing pills. Harvard Health Publishing confirms that because these products are absorbed through the skin, much less of the drug enters your bloodstream. That means fewer side effects on your stomach, kidneys, or heart compared to oral NSAIDs like ibuprofen or naproxen, which can cause internal bleeding in 1-2% of regular users.

But safety depends entirely on how you use them.

• Don’t use them on broken, cut, or sunburned skin. Damaged skin absorbs chemicals faster. That’s how lidocaine overdose happens.
• Never combine them with heating pads, hot water bottles, or electric blankets. Heat increases absorption. That’s how menthol burns occur.
• Avoid the eyes, nose, and mouth. Capsaicin and menthol can cause severe irritation. One accidental touch to the eye can mean hours of pain and a trip to the ER.
• Don’t use them for more than 7 days without checking with a doctor. If pain lasts longer, it’s not just a muscle strain. It could be something serious.
• Stop using if your skin turns red, blisters, or peels. That’s not “working”-that’s a reaction.

People with kidney disease, liver problems, or heart conditions should talk to a pharmacist before using any topical pain reliever. Even though these products seem local, they still enter your system. Diclofenac gel, for example, is an NSAID. It can raise blood pressure and affect kidney function, even when applied topically.

The Hidden Risk: Assumptions and Misuse

Most people assume OTC means “safe.” That’s the biggest mistake.

Mayo Clinic’s Dr. Laurie Danielson points out that patients rarely mention topical pain relievers during doctor visits. They think, “It’s just a cream.” But that’s exactly when problems happen. Someone with high blood pressure uses a menthol patch every day. Someone with diabetes applies capsaicin to numb feet without realizing their skin is already fragile. Someone uses a lidocaine gel after getting a tattoo-because they saw it online.

There’s also the issue of tolerance. Over time, your body gets used to capsaicin or menthol. You start using more, or more often. That’s how minor irritation turns into chemical burns. The Cleveland Clinic warns that analgesics can become less effective over time. That doesn’t mean you need more-it means you need to stop and reassess.

And don’t forget interactions. If you’re on blood thinners, NSAIDs like methyl salicylate or diclofenac can increase bleeding risk-even through the skin. If you’re on multiple medications, ask your pharmacist. They see these interactions every day.

What the Regulators Are Doing

Health Canada responded to the menthol burn risk by updating labeling requirements in 2017. Every product now must clearly warn users about the possibility of serious skin burns. That’s progress.

The FDA has taken a harder line on lidocaine. They don’t just warn-they act. In 2023, they issued formal warning letters to six companies selling illegal high-dose lidocaine products. They’ve seized inventory. They’ve demanded recalls. And they’ve made it clear: they’re using every tool available to stop these products.

But the market is still flooded with unregulated products. Many are sold on Amazon, Etsy, or small websites that don’t follow U.S. or Canadian rules. If a product claims to be “professional strength,” “dermatologist approved,” or “for use before laser treatments,” be skeptical. Check the label. If lidocaine is listed above 4%, it’s illegal. If it doesn’t list ingredients at all? Don’t buy it.

What You Should Do Today

Here’s what to do right now to stay safe:

1. Look at every topical pain reliever you have at home. Check the active ingredients. If it says “menthol,” look for the burn warning on the label. If it says “lidocaine,” check the percentage. If it’s over 4%, throw it away.
2. Stop using any product on broken, irritated, or recently treated skin.
3. Never use heat with these products. Ever.
4. Wash your hands after applying capsaicin or menthol. Use gloves if you can.
5. If you’ve been using a topical pain reliever for more than a week and it’s not helping, see a doctor. Pain that lasts is a symptom, not just an annoyance.

Topical pain relievers can be a great tool. They help people avoid pills, reduce systemic side effects, and manage pain without opioids. But they’re not harmless. They’re medications. And like all medications, they need to be used with care.

Frequently Asked Questions