Lidocaine

Boxed warning:

Do not use lidocaine to treat teething pain in children. Use in infants and young children can cause serious harm, including death.

What is lidocaine?

Lidocaine, also known as lignocaine, is a synthetic organic compound used in a wide range of applications as an antiarrhythmic and anesthetic drug. It comes in many different forms.

What is lidocaine used to treat?

Lidocaine is approved by the US Food and Drug Administration (FDA) for use as a local or regional anesthetic.¹ It is also used in hospital settings as an antiarrhythmic agent — a drug that treats irregular heart rhythms.

When used for local anesthesia, lidocaine prevents pain, itching, burning, aching, and any other type of discomfort in the area where it is applied or injected. It works by blocking pain signals from reaching the brain, which makes it an effective painkiller for minor burns, scrapes, cuts, insect bites, eczema, and hemorrhoids.

Lidocaine is also a popular local anesthetic for some medical procedures, such as the insertion of catheters, cannulas, and breathing tubes. It is useful for reducing discomfort and pain experienced with needle punctures, minor surgery (such as suturing a wound or draining an abscess), and contractions during labor.

Apart from its use in hospitals, lidocaine is widely available as over-the-counter (OTC) creams, patches, and sprays. These medications are for topical use to help manage itching, sunburn, joint pain, skin irritation, and pain from procedures such as tattoos, piercings, and microblading.

Dosage forms and strengths

Lidocaine is available in many forms for topical application, injection, or infusion. Each of these may have different strengths to suit their particular application and usage. These include the following:

• Topical formulations:

  • Spray: 0.5% and 4%

  • Cream: 3%, 4%, and 5%

  • Lotion: 2.75%, 3%, and 3.5%

  • Patch: 4% and 5%

  • Transdermal film: 3.5% and 4%

  • Extended-release transdermal film: 1.8% and 5%

  • Ointment: 4% and 5%

  • Gel: 2%, 2.8%, 3%, and 4%

  • Swab: 3% and 4%

  • Solution: 4% and 10%

  • Oral solution (and dental): 2%

  • Rectal suppository: 50mg

  • Rectal cream: 3%, 3.88%, 4%, 4.12%, and 5%

  • Ophthalmic gel: 3.5%

  • Urethral jelly: 2%

  • Foaming soap: 4%

• Injectable solution: 0.25%, 0.5%, 1%, 1.5%, 2%, and other specific forms based on usage

• Infusion solution (IV formulation in 5% dextrose solution): 100, 200, 400, and 800mg/100mL

Ensure you follow the instructions provided by the medication’s manufacturer and your pharmacist or doctor when using topical OTC lidocaine products. For prescription lidocaine, always follow your doctor’s instructions.

In the hospital, lidocaine injections and infusions will be administered by qualified medical professionals.

How do you take lidocaine?

Each of the different forms of lidocaine is designed for easy and effective application, depending on the medical problem being treated. For example, pain, itching, irritation, and burning caused by hemorrhoids are best treated by applying lidocaine cream to the affected area. In this case, the preferred dosage is 1–4 pumps of cream applied 3–4 times daily.

You can also apply lidocaine ointment for muscle or joint pain. Apply a thin layer 3–4 times daily (every 6–8 hours) or 1–4 pumps daily if you’re using prescription-strength lidocaine gel. Do not apply more than 16 pumps in a 24-hour period.

For general skin irritation, such as sunburns, insect bites, scrapes, and minor cuts, apply lidocaine spray, gel, lotion, or cream to the affected area 3–4 times daily.

You can also use lidocaine foaming soap for general skin irritation and minor skin procedures, such as laser hair removal, tattooing, filler injections, and microblading. Apply 2–3 pumps to the area, rub the foam gently into the skin, leave it for 5–10 minutes to be absorbed, then rinse and air-dry.

When using lidocaine to manage eczema, itching, nerve pain, and pain from injections and vaccines, always follow the instructions given by your doctor or pharmacist.

Lidocaine sprays are also very popular for managing premature ejaculation in men. In this case, the medication is sprayed onto the penis before sexual intercourse to reduce nerve sensitivity. Use the spray as indicated by the manufacturer.

Lidocaine transdermal patches are used for the treatment of nerve pain and should be applied once daily to a clean, dry area of skin that does not have scars, cuts, or irritation. It should be placed on or near the area with the most pain or discomfort, but never continuously for more than 12 hours. You can use it for 12 hours, then take 12 hours off.

Seeing results

Lidocaine provides an almost immediate response when used as a local or regional anesthetic. Lidocaine ointment generally takes effect in 3–5 minutes.² Depending on the dosage and your body’s metabolism, the numbing effect can remain for 30 minutes to three hours.

Use lidocaine patches on any skin that isn’t affected by wounds, bruises, cuts, burns, scratches, or rashes. Lidocaine patches can deliver pain relief within 30 minutes of application and last up to 12 hours.³ In some cases, it may take up to four weeks for you to get maximum pain relief when managing persistent neuropathic pain.⁴

Lidocaine spray tends to reach maximum effectiveness within 20 minutes of application when used for premature ejaculation and can last for up to three hours.⁵

In hospital use, a lidocaine injection given for arrhythmia can restore normal heart rhythm within 15–20 minutes of administration.⁶

Who should not take lidocaine?

Even though lidocaine is generally safe, some people shouldn’t use the drug due to the risk of serious side effects.

Methemoglobinemia poses the biggest risk to lidocaine users. It is a serious blood disorder in which abnormal amounts of methemoglobin (a type of hemoglobin) are produced, which can affect the distribution of oxygen in the body.

People using high amounts of lidocaine are at risk of developing methemoglobinemia, especially children under six months of age, older adults, and patients with certain congenital disorders. Seek immediate medical attention if you notice unusual drowsiness, dullness, weakness, fatigue, sluggishness, seizures, and shallow breathing after using lidocaine.

Other risk factors include the following:

• Pregnancy and lactation

• Allergies to any medicine, foods, preservatives, and food dyes

• Neurological disorders, such as epilepsy and porphyria

• Diseases affecting the brain and spinal cord

• Heart problems, except those indicated for treatment with lidocaine

• Low potassium levels

• Difficulty breathing or low oxygen levels

• Problems with blood clotting

Let your doctor know if you have any of these conditions so that they can decide if lidocaine is suitable for you.

Potential side effects of lidocaine

Lidocaine may cause mild to severe side effects. Although serious side effects are rare, you should inform your doctor immediately if you experience any of the following:

• Hives, rashes, blisters, or bruising at the site of application

• Difficulty breathing and swallowing

• Nausea or vomiting

• Swelling of the face, throat, tongue, lips, eyes, hands, lower legs, feet, or ankles

• Hoarseness or unusual thirst

• Seizures, confusion, dizziness, or fainting

• Weakness, fatigue

• Pale, gray, or blue skin

• Headache, shortness of breath, lightheadedness, or fainting

• Twitching

• Blurry vision

• Low blood pressure

• Abnormally fast or slow heart rate or palpitations

• Cough

• Dark urine

• Ringing in the ears

• Slurred speech

These side effects may result from lidocaine overdose or adverse reactions. The medication can also cause coma or death, so it’s important to inform your doctor or go to the emergency department immediately if you notice any of these symptoms.

Lidocaine injections and infusions can also result in toxicity and adverse effects, including headaches, dizziness, seizures, mental status changes, low blood pressure (hypotension), loss of consciousness, and cardiac arrest.⁷ Typically, this form of the drug will be given in a hospital setting, where the patient can be monitored for any adverse reactions and treated.

Overdose

Although lidocaine is generally safe, an overdose is possible if too much of the drug is absorbed into the bloodstream.

Children and infants are more vulnerable to lidocaine overdose.

Whether applied topically or by injection, lidocaine becomes toxic to the body when it exceeds levels of 4.5mg/kg.⁸ However, toxicity depends on the rate of absorption and blood flow in the area.

A lidocaine overdose can result from accidental injection into an artery, applying too much lidocaine, applying topical lidocaine on broken skin, or mixing lidocaine with other local anesthetics. Lidocaine patches can also increase the risk of overdose if you cut the patch, apply heat to the area, or place the patch on compromised skin.

Lidocaine is structurally similar to cocaine, so using the two simultaneously increases the risk of overdose.

Allergy information

Serious allergic reactions to lidocaine injections and topical applications are rare. True allergies cause symptoms, such as anaphylaxis, hyperventilation, nausea, vomiting, and changes in heart rate or blood pressure.

Lidocaine almost never elicits such serious reactions, except in cases of overdose or if you have existing nervous and neurological conditions.⁹ More common allergic reactions include contact dermatitis, swelling, or urticaria (round, itchy welts on the skin), usually as a result of local injections of lidocaine.

Long-term use of lidocaine

Lidocaine can be an effective solution for the management of long-term pain, discomfort, or irritation because it doesn’t lead to physical dependence, addiction, or tolerance.

In one study, 20 patients with neuropathic pain were successfully treated with a 5% lidocaine plaster.¹⁰ After three years, ten (50%) of the patients were still using the plaster with no reduction in effectiveness. At five years, eight patients (40%) continued to use the plasters and experienced the same pain relief. None of those who discontinued the treatment did so because of a lack of effectiveness or serious side effects. This indicates that lidocaine can be used successfully for long-term therapy.

Lidocaine and pregnancy

Although lidocaine is generally considered safe during pregnancy, the drug crosses the placenta and is also found in breast milk. Care should be taken when using lidocaine during pregnancy and while breastfeeding. Lidocaine should only be used in these situations when the benefits outweigh the potential risks.

Lidocaine has been designated by the FDA as a pregnancy category B medication. This means it has no demonstrated risk to human babies, but medical supervision is necessary when choosing to use it during pregnancy.

Missed doses

If you miss a dose of topical lidocaine, apply it as soon as possible. If it’s almost time for your next dose, skip the missed dose and continue your regular dosing schedule. Don’t apply additional patches or apply extra cream, ointment, or spray to make up for the missed dose.

Drug interactions

Some drugs are contraindicated with lidocaine. This means taking both drugs at the same time could cause adverse effects or change how the drugs work. Some drugs can be taken at the same time with close monitoring.

Common lidocaine interactions include the following:

• Medication that controls the heartbeat, such as amiodarone (Cordarone and Pacerone)

• Blood pressure medication, such as metoprolol (Lopressor, Toprol XL, and Kapspargo Sprinkle) and atenolol (Tenormin)

• Warfarin (Coumadin and Jantoven) for blood clots

• Some nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin

• Seizure medications, such as phenytoin (Dilantin and Phenytek), primidone (Mysoline), carbamazepine (Carbatrol, Epitol, Equetro, Tegretol, and Teril), and sodium valproate

• Some anesthetics

• Some muscle relaxants, such as suxamethonium

• Malaria drugs, such as chloroquine phosphate

• Medication containing nitrates and nitrites (nitric oxide, nitroglycerin)

Some forms of lidocaine may be safe (such as topical creams and sprays) even if you are taking one of these medications. Your doctor can tell you whether it’s safe to take your lidocaine formulation with other drugs.

Stopping lidocaine

Since lidocaine doesn’t cause physical dependence, addiction, or tolerance, you should not experience withdrawal effects when you stop using the drug.

Drug approval history

Lidocaine was discovered by Swedish chemists in 1946 and has been accepted for medical use since 1948. It was first approved by the FDA on May 7, 1959, as an anesthetic and is now one of the most prescribed medications in the US.¹¹

Lidocaine is also on the World Health Organization’s List of Essential Medicines.

Tips for taking lidocaine

These are some general dos and don’ts you should consider to avoid or minimize potential side effects.

• Do not ingest topical lidocaine or allow it to enter your eyes, nose, mouth, rectum, or vagina. If it does, rinse the area immediately with water.

• Use the smallest dosage required to numb the skin and relieve pain. This means

  • Don’t apply it to large areas at once.

  • Don’t use multiple patches in the same area.

  • Don’t leave patches on for more than 12 hours at a time.

  • Don’t exceed the dosage prescribed by a health professional or manufacturer.

• Don’t use lidocaine for longer than required.

• Don’t cover, bandage, or heat areas with a lidocaine patch.

• Never apply lidocaine to an area with open wounds, sores, swollen skin, or deep puncture wounds.

• Lidocaine shouldn’t be used on children under 12 years of age, pregnant women, or breastfeeding mothers unless directed by a health professional.

• If you use lidocaine for oral application in your mouth or throat, don’t chew or swallow food for an hour afterward.

• Don’t use more than one type of medication containing lidocaine at any one time. For example, don’t mix patches, soaps, gels, sprays, and creams.

• Always let your doctor know if you have a heart condition, liver or kidney disease, problems with blood circulation, or allergies.

Frequently asked questions

Can I drink alcohol while taking lidocaine?

You shouldn’t drink alcohol for 48 hours after receiving a lidocaine injection or infusion. Doing so can cause your blood pressure levels to fall to a point where you feel dizzy and faint since both alcohol and lidocaine can dilate the blood vessels.

Can lidocaine damage your heart?

No. Research indicates that lidocaine is safe even for patients with underlying heart conditions that predispose them to abnormal cardiac rhythms.¹² In fact, lidocaine is used to restore a normal heartbeat in patients with fast or irregular heartbeats.

How long does lidocaine stay in your system?

Lidocaine has a half-life of 1.5–2 hours and about 70–90% of it is metabolized in the liver.⁸ ⁷ After a local injection, its effects should wear off in about three hours. Patches and other formulations for topical application allow lidocaine to be absorbed much more slowly.