Lidocaine

Key facts

• Lidocaine is a local anesthetic. Applied as a cream, gel, spray, patch or injection, it numbs a specific area of skin or tissue for minor procedures, dental work, or short-term relief of pain and itching.
• It starts working within minutes, and numbness typically lasts one to a few hours depending on the strength and form used.
• Applying too much over too large an area, on broken or heavily irritated skin, or under a dressing or wrap lets more lidocaine reach the bloodstream than intended; too much can cause seizures, an irregular heartbeat, or cardiac arrest. Use only the amount and area stated on the label.
• Seek urgent care for ringing in the ears, confusion, a racing or irregular heartbeat, seizures, or trouble breathing after use.

What Lidocaine treats

Lidocaine numbs pain from minor burns, cuts, insect bites, sunburn and hemorrhoids, and provides local anesthesia before injections, dental work and minor skin or surgical procedures. Some throat sprays and gels numb the mouth or throat before a procedure. It relieves pain and itching in the treated area only; it does not treat the underlying cause and has no effect once it wears off.

How Lidocaine works

Nerves send pain signals by moving charged particles across their membrane. Lidocaine blocks the channels nerves use to do this, so the nerve cannot fire and the brain does not register pain, touch or temperature from that area until the drug wears off.

Before you take it

• Do not use lidocaine if you are allergic to it or to other local anesthetics.
• Do not apply it to large areas of skin, broken or infected skin, or under airtight dressings unless a product is specifically labeled for that use, since this raises the amount absorbed into your blood.
• Tell your prescriber about heart rhythm problems or if you take other anti-arrhythmic medicines, since their effects can add to lidocaine's.
• Numbed skin or a numbed mouth can hide injury; avoid heat, ice, chewing, or driving until normal sensation returns.

Side effects

Common effects include mild burning or stinging at the site, redness, itching, and temporary numbness beyond the treated area.

Seek urgent care for:

• Ringing in the ears, a metallic taste, confusion, or slurred speech.
• Seizures or muscle twitching.
• A fast, slow or irregular heartbeat, or fainting.
• Difficulty breathing or swelling of the face or throat.

Safety essentials

• Systemic toxicity from over-absorbed lidocaine is a medical emergency: it can cause seizures and life-threatening heart rhythm problems. Never exceed the labeled dose, treatment area or duration, and never apply extra product because it "isn't working".
• Keep lidocaine away from the eyes and, unless specifically directed, away from mucous membranes, and use extra caution in young children, where a given dose reaches a higher concentration in a smaller body.
• If a lidocaine patch or gel is prescribed, use only one at a time unless told otherwise, and remove old patches before applying a new one.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.