Can Lidocaine Cause Diarrhea? Understanding the Connection

October 8, 2025 •

4 min read

While lidocaine is a widely used local anesthetic, some formulations list diarrhea as a potential side effect [1.2.1, 1.3.2]. The likelihood of experiencing this often depends on the method of administration and systemic absorption.

Quick Summary

Yes, certain forms of lidocaine can cause diarrhea, although it is more common with oral or systemic use than with topical patches. This reaction relates to how the body absorbs the medication.

Key Points

Direct Answer: Yes, lidocaine can cause diarrhea, though it is not one of the most common side effects [1.2.1, 1.3.2].
Formulation Matters: The risk is highest with oral/viscous lidocaine that enters the digestive system [1.3.1, 1.4.3].
Topical Use is Low-Risk: Topical patches and creams applied to intact skin have minimal systemic absorption, making diarrhea a very rare side effect [1.6.5].
Other GI Effects: Nausea and vomiting are also potential gastrointestinal side effects, particularly with oral use or systemic exposure [1.3.1, 1.2.4].
Mechanism: Side effects like diarrhea occur when lidocaine is absorbed systemically, affecting various body systems beyond the local application site [1.5.4].
Management: If diarrhea occurs, stay hydrated and eat a bland diet. Always consult a doctor before taking anti-diarrheal medication [1.8.1, 1.8.4].
When to See a Doctor: Seek immediate medical attention if diarrhea is accompanied by severe symptoms like confusion, seizures, or difficulty breathing, as these could indicate toxicity [1.2.6, 1.7.4].

What is Lidocaine and How Does It Work?

Lidocaine is a versatile medication classified as a local anesthetic and a class-Ib antiarrhythmic agent [1.5.4, 1.9.3]. First made available in 1948, its primary function is to cause temporary numbness or loss of feeling in a specific area of the body [1.9.3, 1.9.1]. It achieves this by blocking voltage-gated sodium channels in nerve cell membranes [1.5.2, 1.5.5]. This action prevents nerves from sending pain signals to the brain, effectively numbing the targeted region without causing a loss of consciousness [1.9.2, 1.5.2].

Lidocaine comes in various forms, each designed for different medical purposes [1.9.2]:

Injectable solutions: Used by healthcare providers for minor surgical procedures, dental work, and nerve blocks [1.9.1, 1.9.5].
Topical creams, ointments, and jellies: Applied to the skin to relieve pain and itching from minor burns, insect bites, or cuts [1.9.2].
Topical patches: Used to manage localized nerve pain, such as the pain associated with shingles (postherpetic neuralgia) [1.9.2].
Viscous (oral) solutions: Used to numb the mouth and throat, often to reduce the gag reflex during dental impressions or to treat painful inflammation of the urethra [1.9.2].

Can Lidocaine Cause Diarrhea?

Yes, diarrhea is listed as a possible side effect of lidocaine, along with other gastrointestinal (GI) symptoms like nausea, vomiting, and stomach pain [1.2.1, 1.3.2]. However, the risk is not the same across all forms of the medication. The likelihood of experiencing systemic side effects, including digestive issues, increases when the drug is absorbed into the bloodstream in significant amounts [1.5.4].

Gastrointestinal side effects are more commonly associated with forms of lidocaine that are ingested or have a higher potential for systemic absorption [1.3.1]. For example, oral viscous lidocaine, which is swished in the mouth and may be swallowed, is more likely to cause GI upset than a topical patch applied to intact skin [1.3.1, 1.4.3]. When lidocaine is used in procedures involving the digestive tract or throat, symptoms like nausea and vomiting can also occur [1.3.1]. While the exact mechanism for drug-induced diarrhea can be complex and multifactorial, it often involves changes in gut motility or fluid secretion [1.5.1].

Lidocaine Formulations and Risk of Diarrhea

The way lidocaine is administered plays a crucial role in its side effect profile. Topical applications on a small area of intact skin generally lead to minimal systemic absorption, making side effects like diarrhea rare. Conversely, formulations that enter the digestive system or are administered in ways that lead to higher plasma concentrations carry a greater risk.


Lidocaine Formulation	Primary Use	Risk of Causing Diarrhea	Rationale
Topical Patch (e.g., Lidoderm)	Localized nerve pain (shingles) [1.9.2]	Very Low	Minimal systemic absorption through intact skin. Side effects are typically local, like skin irritation [1.6.5]. While systemic effects are possible, GI issues are not common [1.6.2].
Topical Cream/Ointment	Minor skin pain, cuts, burns [1.9.2]	Very Low	Similar to the patch, absorption is low when applied to small areas of intact skin. Risk increases if applied to large areas or broken skin.
Injectable Lidocaine	Local anesthesia for procedures [1.9.1]	Low to Moderate	Diarrhea is not a primary side effect, but systemic toxicity can occur if accidentally injected into a blood vessel, leading to various symptoms including loss of bowel control in severe cases [1.7.4, 1.2.5]. Nausea and vomiting are more commonly reported GI effects [1.2.4].
Viscous/Oral Solution	Numbing mouth/throat [1.9.2]	Moderate to High	This form is ingested or comes in direct contact with the GI tract, increasing the likelihood of digestive side effects like nausea, vomiting, and potentially diarrhea [1.3.1, 1.4.3].

Managing Medication-Induced Diarrhea

If you experience diarrhea after using lidocaine, especially the oral/viscous form, it's important to manage the symptoms and consult a healthcare professional. Most cases are mild and resolve on their own after the drug is discontinued [1.8.3].

Here are some general tips for managing medication-induced diarrhea:

Stay Hydrated: Drink plenty of fluids like water, broth, or oral rehydration solutions to replace lost fluids and electrolytes [1.8.1].
Adjust Your Diet: Gradually introduce low-fiber foods such as rice, toast, eggs, and chicken [1.8.4]. Avoid high-fiber, fatty, or spicy foods, as well as caffeine and alcohol, which can irritate the bowels [1.8.2, 1.8.4].
Consult Your Doctor: Inform your doctor about the side effect. They can confirm the cause and advise whether to stop or change the medication. Do not use anti-diarrheal medications without a doctor's approval, as they can sometimes worsen certain conditions [1.8.1, 1.8.4].

When to Seek Medical Attention

While mild diarrhea may not be a cause for alarm, you should contact a doctor immediately if you experience it along with other serious symptoms. These can be signs of lidocaine toxicity or a severe allergic reaction [1.7.4, 1.2.6].

Seek emergency help if you have:

Severe dizziness or drowsiness [1.2.6]
Confusion or blurred vision [1.2.6]
Ringing in the ears [1.2.6]
Tremors or seizures [1.7.4]
Slow heart rate or difficulty breathing [1.4.6]
Hives, rash, or swelling of the face, lips, or tongue [1.2.6]

Conclusion

So, can lidocaine cause diarrhea? The answer is yes, but the risk is heavily dependent on the formulation. Oral or viscous lidocaine carries a higher risk due to its interaction with the gastrointestinal system [1.3.1]. In contrast, topical forms like patches and creams are unlikely to cause diarrhea when used correctly on intact skin because very little of the drug enters the bloodstream [1.6.5]. While diarrhea is a listed side effect, it's less common than other potential reactions like local skin irritation or CNS symptoms like dizziness with higher-dose forms [1.2.3, 1.6.4]. If you are prescribed lidocaine and have concerns about this or any other side effect, discussing them with your healthcare provider is the best course of action.

For more information on the safe use of lidocaine, you can consult authoritative resources like MedlinePlus.

Frequently Asked Questions

It is very unlikely. The lidocaine patch works locally with minimal absorption into the bloodstream, so systemic side effects like diarrhea are rare [1.6.2, 1.6.5]. The most common side effects are skin reactions at the application site, such as redness or irritation [1.6.5].

Viscous or oral lidocaine solutions are most likely to cause diarrhea because they are ingested or come into direct contact with the gastrointestinal tract [1.3.1, 1.4.3].

You should stay hydrated by drinking plenty of fluids and eat a bland, low-fiber diet [1.8.1, 1.8.4]. Contact your doctor to report the side effect; they can provide guidance and determine if any changes to your treatment are needed.

By itself, mild diarrhea is generally not considered a sign of a serious reaction. However, if it is accompanied by other symptoms like severe dizziness, confusion, tremors, seizures, or difficulty breathing, it could be a sign of systemic toxicity, which requires immediate medical attention [1.2.6, 1.7.4].

In most cases, drug-induced diarrhea resolves within a few days after the medication is discontinued [1.8.3]. If it persists, consult your healthcare provider.

It is not a common side effect. Gastrointestinal issues from a standard dental injection are rare. Systemic side effects are possible but usually involve the central nervous or cardiovascular systems, such as dizziness or changes in heart rate [1.2.4, 1.7.4].

Other common gastrointestinal side effects associated with lidocaine, particularly when absorbed systemically, include nausea and vomiting [1.2.4, 1.3.3]. Constipation has also been reported [1.2.3].