How Does Relador Work? Mechanism of Action Explained in Plain English

You apply Relador to your skin, wait an hour, and then — amazingly — the needle doesn't hurt. How does that work? The science behind how Relador (lidocaine 2.5%/prilocaine 2.5% cream) numbs your skin is actually fascinating and not as complicated as it sounds. Here's a clear explanation.

How Does Your Skin Feel Pain in the First Place?

Before understanding how Relador works, it helps to know how pain sensing works. Your skin is full of tiny nerve endings called nociceptors — pain-sensing nerve fibers that detect tissue damage, pressure, heat, or chemicals. When something hurts (a needle, a cut, a burn), these nerve endings generate an electrical signal called an "action potential."

An action potential works like a relay race. Sodium ions rush into the nerve cell through special gates called voltage-gated sodium channels, triggering a wave of electrical activity that travels up the nerve fiber, through the spinal cord, and ultimately to your brain — which is where you consciously experience pain. Block those sodium channel gates, and you block the signal entirely.

How Lidocaine and Prilocaine Block Pain: Sodium Channel Blockade

Both lidocaine and prilocaine belong to a drug class called amide local anesthetics. Their mechanism is called sodium channel blockade. Here's how it works step by step:

After you apply Relador cream to your skin, the lidocaine and prilocaine molecules slowly penetrate through the outer skin layers (epidermis) and into the dermis where nerve endings are located.

The anesthetic molecules enter the nerve cell membrane and bind to voltage-gated sodium channels from the inside.

By binding to these channels, lidocaine and prilocaine physically block sodium ions from rushing in — like putting a cork in a pipe.

Without sodium ion flow, no action potential can be generated. The nerve is "silenced" — it can no longer send a pain signal.

The result: the procedure area is numb. You may feel pressure or movement, but not sharp pain.

Why Does Relador Use Both Lidocaine AND Prilocaine?

The combination of lidocaine and prilocaine in Relador is not accidental — it's based on an important chemistry concept called the eutectic mixture.

Individually, both lidocaine and prilocaine are solid or semi-solid at room temperature. But when mixed together in the exact 1:1 ratio used in Relador, something interesting happens: the melting point of the mixture drops dramatically. The combined mixture becomes a liquid oil at room temperature — this is what a "eutectic mixture" means.

Why does this matter? Because a liquid penetrates skin far better than a solid or semi-solid. The eutectic property of lidocaine-prilocaine cream is what makes it able to penetrate through intact, healthy skin — something most topical anesthetics cannot do effectively. This is Relador's key differentiator from simple topical benzocaine gels that only work on mucous membranes.

Why Do You Need to Wait 45–60 Minutes?

Skin is an effective barrier — that's one of its jobs. Even with the eutectic mixture advantage, it takes time for lidocaine and prilocaine molecules to penetrate from the surface down through the epidermis and reach the nerve endings in the dermis below. Studies show that maximal dermal anesthesia is typically achieved after 60 minutes of application under an occlusive dressing.

The occlusive dressing (the Tegaderm film in the Relador Pak) is essential because it:

Prevents the cream from drying out or being wiped off

Increases the concentration gradient (pressure) pushing the drug into the skin

Warms the skin slightly, which also improves penetration

How Long Does the Numbness Last?

Once the cream is removed, the numbness (anesthesia) typically persists for:

Approximately 1–2 hours for superficial anesthesia after a 60-minute application

Deeper tissue numbness may last longer with extended application times

After the anesthesia wears off, normal nerve function is completely restored. There is no permanent effect on nerves from appropriate use of Relador.

Does Relador Only Block Pain, or Does It Numb Everything?

Topical anesthetics like Relador primarily block small, unmyelinated (C-fiber) pain and temperature nerve fibers. At normal topical doses, they generally do not completely block larger motor nerve fibers. This means:

You can still feel pressure, touch, and vibration in the numb area (these are carried by different nerve types)

You can still move your limbs normally — this is purely surface anesthesia

Sharp pain from needle puncture or cutting should be significantly reduced or eliminated

To learn more about Relador's uses and how to apply it, see our guide to what Relador is and how it's used. And for information on side effects and safety, see Relador side effects: what to expect.