Where Should You Not Put Numbing Cream? Understanding the Risks

October 7, 2025 •

4 min read

In 2007, the U.S. Food and Drug Administration (FDA) issued a public warning about potentially life-threatening risks, including seizures and irregular heartbeats, associated with the misuse of topical anesthetics. Knowing precisely where you should not put numbing cream is a critical piece of safety information, as improper application can dramatically increase the risk of severe systemic side effects, beyond simple skin irritation.

Quick Summary

Applying numbing cream incorrectly to sensitive areas, broken skin, or excessive body surface area can cause dangerous systemic absorption. Severe side effects, including cardiac and neurological issues, can occur, emphasizing the need for strict adherence to safety guidelines.

Key Points

Avoid Mucous Membranes: Never apply numbing cream to the eyes, nose, mouth, ears, genitals, or anus, as these areas are highly sensitive and absorb medication rapidly.
Do Not Apply to Broken Skin: Avoid using numbing cream on open wounds, scrapes, burns, rashes, or irritated skin, as a compromised skin barrier significantly increases the risk of toxic absorption.
Limit Application to Small Areas: Applying cream over a large body surface area is dangerous and can lead to excessive absorption and systemic toxicity.
Never Use Occlusion or Heat: Covering the treated area with plastic wrap or using a heating pad accelerates absorption and has been linked to severe overdoses and death.
Follow Dosage and Time Limits: Stick to the recommended amount and duration specified in the product instructions to prevent toxic levels from entering the bloodstream.
Recognize Overdose Symptoms: Be aware of signs of systemic toxicity, such as dizziness, confusion, irregular heartbeat, or difficulty breathing, and seek immediate medical help if they occur.

Why Numbing Creams Require Caution

Numbing creams, or topical anesthetics, work by blocking nerve signals in the skin to temporarily relieve pain and discomfort. They are a mixture of active ingredients, often including lidocaine, benzocaine, or prilocaine. While effective for minor procedures and pain, misuse can turn these helpful products into a serious health risk. The skin is a protective barrier, but certain conditions and application methods can compromise it, leading to excessive absorption of the anesthetic into the bloodstream. When this happens, the active ingredients can reach toxic levels, affecting the heart, brain, and other vital organs, sometimes with fatal consequences.

Areas to Avoid When Applying Numbing Cream

It is crucial to understand the anatomical sites where numbing cream application is dangerous. These areas are prone to faster absorption or are inherently sensitive, increasing the risk of both local and systemic harm.

Mucous Membranes and Sensitive Areas

Eyes: Applying numbing cream near or in the eyes can cause severe irritation and corneal abrasion. The product can also be absorbed through the delicate mucous membranes. If contact occurs, rinse the eyes immediately with water for at least 15 minutes and seek medical help.
Ears: Avoid applying the cream inside the ear canal, especially in cases of suspected middle ear infection. Absorption in this sensitive area can lead to serious hearing problems.
Inside the Mouth and Throat: Most topical numbing products are not formulated for internal use. If applied inside the mouth or throat, they can numb the swallowing reflex, leading to choking. Some products, like prescription-only lidocaine viscous, are specifically designed for oral use but must be used under strict medical supervision.
Genitals and Anus: Unless specifically directed by a doctor, numbing creams should not be applied to the genitals or anus. The high vascularity and delicate skin in these areas can significantly increase absorption and the risk of systemic toxicity.

Broken or Irritated Skin

The most dangerous risk of numbing cream application comes from using it on skin with a compromised barrier. This includes:

Open Wounds and Scrapes: The absence of an intact skin barrier allows for rapid, uncontrolled absorption of the anesthetic into the bloodstream, bypassing the protective skin layers.
Burns: Similarly, burned skin offers no protection against absorption. The risk of toxicity is extremely high when applying numbing agents to severe burns.
Rashes, Swelling, and Redness: Inflamed skin increases the rate of absorption. Applying cream to skin that is red, swollen, or rashy can lead to higher systemic levels of the medication.
After a Tattoo: Numbing cream is for pre-procedure use only. It should never be applied to broken skin after the tattoo process has begun, as this can cause the anesthetic to enter the bloodstream directly and lead to toxicity.

Practices that Increase Absorption and Risk

In addition to the location of application, certain practices can dramatically increase the danger of using numbing cream.

Applying to Large Areas: Covering a large body surface area, like an entire leg or back, is extremely dangerous. The total dose of anesthetic absorbed can be fatal, as seen in documented cases of toxicity from pre-laser hair removal cream application.
Occlusive Wraps and Heat: Wrapping the area with plastic wrap (occlusion) or applying heat (e.g., heating pads, electric blankets) significantly increases the skin's temperature and absorption rate. This practice is a major factor in many overdose cases.
Excessive Amounts or Duration: Using more cream than recommended or leaving it on for an extended period of time allows for a greater quantity of the active ingredient to be absorbed. Always follow the instructions regarding the amount and duration of application.

Safe vs. Unsafe Numbing Cream Application

To highlight the critical difference between safe and dangerous practices, the following comparison table provides a clear overview:


Attribute	Safe Application	Unsafe Application
Application Site	Small, intact area of healthy skin.	Large body surface area, mucous membranes (eyes, mouth, genitals), or broken skin.
Skin Condition	Clean, dry, and free of cuts, scrapes, or irritation.	Irritated, cut, swollen, burned, or recently tattooed skin.
Dose and Duration	Smallest amount needed, applied for the recommended duration.	Applying excessive amounts or leaving it on for longer than directed.
Additional Factors	No occlusion or heat applied; perform a patch test beforehand.	Covering the area with plastic wrap or using a heating pad.
Source of Cream	FDA-approved products, ideally with a prescription for higher concentrations.	Unregulated, high-concentration creams from unknown sources.
Monitoring	Aware of potential side effects and signs of toxicity.	Ignoring or unaware of potential severe side effects.

Signs of Systemic Toxicity and When to Seek Help

Serious systemic side effects can occur if too much numbing cream is absorbed. It is vital to recognize the symptoms of an overdose and act immediately.

If you or someone else experiences any of the following symptoms, wipe off the cream and seek immediate medical attention:

Dizziness, drowsiness, or lightheadedness.
Confusion, nervousness, or restlessness.
Numbness or tingling sensation beyond the application area.
Ringing in the ears (tinnitus) or blurred/double vision.
Metallic taste in the mouth.
Bluish discoloration of the skin, lips, or fingernails (a sign of methemoglobinemia).
Irregular, slow, or fast heartbeat.
Difficulty breathing or chest tightness.
Seizures, convulsions, or unconsciousness.

Conclusion

While numbing cream offers a convenient way to manage pain for minor procedures, its safe use is not a matter to be taken lightly. The location of application, the condition of the skin, and the amount used are all critical factors in preventing serious and potentially life-threatening side effects. The FDA and health professionals consistently warn against applying numbing cream to broken skin, large areas of the body, or sensitive mucous membranes. Always use the product exactly as directed, preferably under the guidance of a healthcare professional, and be vigilant for any signs of systemic toxicity. Prioritizing safety through proper use is the only way to benefit from numbing cream without putting your health at risk.

For more information on the dangers of high-concentration, unregulated topical pain relief products, you can review the FDA's public warnings directly.

Frequently Asked Questions

You should not use numbing cream over a large area for a tattoo, as this significantly increases the risk of toxic systemic absorption. For a large piece, it is safer to apply cream to smaller sections or to the most sensitive areas, and always consult with your tattoo artist and a healthcare provider.

No, it is extremely dangerous to apply numbing cream to broken skin, including cuts, scrapes, or burns. The compromised skin barrier allows the anesthetic to be absorbed too quickly and in high doses, potentially causing severe systemic side effects.

Applying numbing cream to the eyes can cause severe irritation and corneal injury. If accidental contact occurs, rinse your eyes with copious amounts of water for at least 15 minutes and contact a healthcare professional immediately.

While wrapping the cream with an occlusive dressing can increase its numbing effect, it also dramatically increases the risk of toxic absorption and is extremely dangerous. The FDA has warned against this practice, which has been linked to severe overdoses.

Signs of a numbing cream overdose can include dizziness, confusion, ringing in the ears, blurred vision, irregular heartbeat, or difficulty breathing. If you experience any of these symptoms, remove the cream immediately and seek emergency medical attention.

No, numbing cream should only be applied to intact skin before a procedure. Applying it to broken skin after a tattoo or other cosmetic procedure can lead to dangerous absorption of the anesthetic into the bloodstream.

Over-the-counter (OTC) numbing creams are generally safe when used as directed on small, intact skin areas. However, many high-concentration OTC creams marketed for cosmetic procedures are unregulated by the FDA and can pose significant health risks if misused. Always choose FDA-approved products and follow instructions carefully.