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

Every year, millions of people in the UK and beyond reach for a topical pain reliever - a cream, gel, or patch - to ease sore muscles, stiff joints, or nagging arthritis pain. It feels simple: rub it on, wait a few minutes, and the discomfort fades. But what you don’t see on the label could be just as important as what you do. Not all OTC topical pain relievers are created equal, and some carry hidden risks that even experienced users overlook.

What’s Actually in Your Pain Reliever?

OTC topical pain relievers rely on a few key active ingredients, each with its own profile of benefits and dangers. The most common are menthol, a cooling agent that tricks nerves into feeling cold instead of pain, methyl salicylate, a cousin of aspirin that reduces inflammation at the skin’s surface, and capsaicin, the compound that makes chili peppers hot, which depletes pain-signaling chemicals in nerve endings.

Products like Aspercreme Heat Pain Relieving Gel contain exactly 10% menthol - a concentration high enough to deliver strong relief but also enough to cause serious skin burns if misused. Health Canada confirmed this in 2017 after reviewing dozens of cases where people developed second-degree burns after applying menthol-based gels and then covering them with heating pads or tight bandages. The burns weren’t from heat - they were from chemical damage caused by menthol disrupting skin cells. That’s why Canadian labels now clearly warn: “Do not use with heating pads, electric blankets, or hot water bottles.”

Meanwhile, methyl salicylate - found in Bengay and similar products - doesn’t carry the same burn risk. But it’s still a salicylate. If you’re allergic to aspirin or take blood thinners like warfarin, using too much of this ingredient can lead to internal bleeding or bruising. It’s absorbed through the skin, and while less than oral aspirin, it still adds up over time.

Capsaicin is different. It doesn’t numb - it exhausts. Applied regularly, it reduces substance P, the chemical that tells your brain you’re in pain. But it takes work: you need to use it three to four times a day for up to a week before you feel relief. And yes, it stings - sometimes badly. That’s why pharmacists recommend wearing gloves or using a roll-on applicator. If you accidentally rub your eye after applying capsaicin, you’ll know why it’s called “chili pepper extract.”

The Lidocaine Trap

Not all topical pain relievers are legal. In July 2023, the U.S. Food and Drug Administration issued a public warning about products sold online - often marketed for use before or after tattoos, laser treatments, or microdermabrasion - that contain dangerously high levels of lidocaine. These products can contain up to 20% lidocaine, far exceeding the 4% maximum allowed for OTC use.

Why does that matter? Lidocaine is a local anesthetic. At high doses, it can enter your bloodstream and disrupt your heart rhythm, trigger seizures, or stop your breathing. The FDA named six companies - Bella’s Beauty Supply, DermaRoller Store, DermaSelect, DermaWand, DermaFlash, and DermaSweep - for selling these illegal products. Many were sold on Amazon, Etsy, and Instagram shops, often with claims like “numb your pain instantly” or “perfect for sensitive skin.”

There’s no excuse for these products to exist. The FDA has warned about them for over a decade. Yet, they keep popping up. If you bought a patch or gel labeled “10% lidocaine” or “professional strength” without a prescription, you’re using something the government says is unsafe.

When Topical Pain Relievers Are Safer Than Pills

One of the biggest advantages of topical pain relievers is that they don’t flood your whole body with chemicals. Oral NSAIDs like ibuprofen or naproxen can cause stomach ulcers, kidney damage, or raise blood pressure - especially if taken daily. The Mayo Clinic reports that 1-2% of regular oral NSAID users develop gastrointestinal bleeding each year.

Topical versions, by contrast, deliver pain relief where it’s needed with far less absorption. Dr. Christopher Gilligan from Brigham and Women’s Hospital says topical pain relievers are “a safe choice for pain due to soft tissue injury or osteoarthritis” because only small amounts enter the bloodstream. That’s why they’re often the first recommendation for older adults or people with kidney issues who can’t take oral meds.

But “safe” doesn’t mean “risk-free.” Even topical diclofenac - a nonsteroidal anti-inflammatory drug available as a gel - can cause skin rashes, itching, or allergic reactions. And if you apply it over large areas of skin or for weeks on end, you still risk systemic side effects.

How to Use These Products Safely

Here’s what you need to do - and not do - to avoid harm:

• Never apply on broken skin. Cuts, scrapes, rashes, or sunburns increase absorption. A patch on a scraped knee? That’s asking for trouble.
• Avoid heat. Heating pads, warm baths, saunas, or even tight clothing can trap heat and boost absorption. Menthol + heat = chemical burn risk. Capsaicin + heat = worse burning sensation.
• Wash your hands. Always. After applying any cream or gel, wash thoroughly. You don’t want to accidentally rub your eyes or transfer capsaicin to a child’s skin.
• Don’t use more than directed. Most products say “apply 3-4 times daily.” Going beyond that won’t make it work faster - it just increases your risk.
• Check for allergies. If you’re allergic to aspirin, avoid methyl salicylate. If you have sensitive skin, test a small patch first.
• Don’t combine with other pain meds without asking. Using a topical NSAID gel while also taking oral ibuprofen doubles your NSAID load. That’s not twice the pain relief - it’s twice the risk.

When to Stop and See a Doctor

Topical pain relievers are meant for short-term relief - not long-term management. If your pain lasts more than seven days, or if it gets worse instead of better, it’s not a problem you can rub away. It could be a pinched nerve, a torn tendon, or something more serious.

Also, if you notice:

• Redness, swelling, or blistering where you applied the product
• Heart palpitations, dizziness, or trouble breathing after use
• Unusual bruising or bleeding (especially if using methyl salicylate)

Stop using it immediately and call your doctor. These aren’t normal side effects - they’re warning signs.

What’s Missing From the Label?

Most people assume OTC means “safe.” But as Dr. Laurie Danielson from Mayo Clinic points out: “Most people assume over-the-counter (OTC) medications are safe and then overlook discussing their use with their care team.”

That’s the real danger. You’re not just using a cream. You’re using a medicine. And medicines interact. They build up. They affect your organs. Even if it’s not swallowed.

That’s why it’s smart to mention any topical pain reliever you’re using during your next doctor’s visit - even if you think it’s harmless. Your pharmacist can check for interactions. Your GP can tell you if it’s right for your condition. And if you’re on blood thinners, have kidney disease, or are over 65, that conversation could prevent a hospital visit.

Bottom Line: Use Wisely, Not Often

OTC topical pain relievers have a place in modern pain management. They’re convenient, targeted, and often safer than pills. But they’re not magic. They’re chemicals. And like any chemical, they need respect.

Stick to products with clear labels, known ingredients, and approved concentrations. Avoid anything sold online with vague claims like “miracle pain relief” or “professional grade.” And never use them on broken skin, near heat sources, or for more than a week without checking in with a professional.

For most people, used correctly, these products are a smart, low-risk option. But used carelessly? They can turn a simple ache into a serious injury.