Understanding Lignocaine Gel and How It Works
Lignocaine, also commonly called lidocaine, is a local anesthetic used to numb a specific area of the body [1.8.3]. It prevents pain by blocking the nerve signals at the nerve endings in the skin [1.6.2]. Lignocaine works by stabilizing the neuronal membrane, which inhibits the ionic fluxes necessary for the initiation and conduction of pain impulses [1.2.7]. This action effectively stops nerves from sending pain signals to the brain, resulting in a temporary loss of feeling in the area where the gel is applied [1.2.2]. It is available in various forms, including gels, creams, ointments, and patches, and is used for a wide range of applications from minor skin irritations to preparation for medical procedures [1.6.2]. Unlike general anesthetics used for major surgery, lignocaine does not cause unconsciousness [1.6.2].
How Long Does It Take for Lignocaine Gel to Work?
The onset of action for lignocaine gel can vary significantly based on several factors, primarily the application site and whether the skin is intact.
- On Mucous Membranes or Broken Skin: When applied to mucous membranes (like inside the mouth or urethra) or on broken/inflamed skin, lignocaine gel has a rapid onset. The numbing effect typically begins within 3 to 5 minutes [1.2.7, 1.3.1, 1.8.4]. This is because the medication is more readily absorbed in these areas [1.4.2].
- On Intact Skin: For application on healthy, unbroken skin, the time to effect is longer. Most people will start to feel a numbing effect within 30 to 60 minutes [1.2.2, 1.2.4]. Deeper penetration for procedures may require longer application times, sometimes up to 60-120 minutes [1.3.5].
Factors Influencing the Onset and Duration
Several variables can influence how quickly lignocaine gel works and how long the effects last:
- Concentration: Higher concentrations of lignocaine may lead to a faster and more profound effect [1.5.4]. For example, 5% ointment has an onset of 3 to 5 minutes on the appropriate surfaces [1.2.7].
- Application Area: The rate of absorption is determined by the site of application [1.4.3]. The gel is absorbed most rapidly after administration to the tracheobronchial tree and more slowly through intact skin [1.4.2]. Applying the gel over a large surface area can increase absorption into the bloodstream [1.4.1].
- Skin Condition: The gel works faster on damaged or irritated skin compared to healthy, intact skin because the natural barrier (stratum corneum) is compromised [1.4.2, 1.4.6].
- Occlusion: Covering the treated area with a dressing (occlusion) can enhance absorption and speed up the numbing process, but it also increases the risk of systemic side effects [1.4.1, 1.8.2].
- Temperature: Applying heat to the area can increase the absorption rate of lignocaine, which may increase the risk of serious side effects [1.7.1].
- Individual Factors: Each person's metabolism and body chemistry can affect how they respond to the anesthetic [1.2.6]. Conditions like liver or heart problems can prolong the effects of lignocaine as the body takes longer to metabolize it [1.8.1].
Comparison of Topical Anesthetics
Lignocaine is just one of several topical anesthetics available. Here’s how it compares to another common option, benzocaine.
| Feature | Lignocaine Gel | Benzocaine Gel |
|---|---|---|
| Onset of Action | 3-5 minutes on mucous membranes [1.2.7]; may take up to 10 minutes [1.5.2] | Can be faster, around 15-30 seconds for a spray [1.5.1] |
| Duration of Action | Typically longer, around 30-60 minutes [1.5.1, 1.8.3] | Shorter, around 15 minutes [1.5.1] |
| Potency | Considered stronger; a lower concentration (5%) can be as effective as a higher concentration of benzocaine (20%) [1.5.1] | Generally less potent than lignocaine at the same concentration [1.5.1] |
| Common Uses | Minor cuts, burns, insect bites, hemorrhoids, and pre-procedure numbing [1.6.1] | Sore throat (lozenges), toothaches, canker sores, and minor skin irritations [1.5.1] |
| Key Risks | Systemic toxicity if overused, methemoglobinemia (rare) [1.7.3] | Methemoglobinemia (a rare but serious condition) is a known risk [1.5.4] |
Proper Application and Safety Precautions
To ensure lignocaine gel is used safely and effectively, it's crucial to follow proper guidelines.
Application Steps:
- Wash Hands: Always wash your hands with soap and water before and after application, unless you are treating your hands [1.7.1].
- Clean the Area: If practical, cleanse and gently dry the affected area before applying the medication [1.3.2].
- Apply a Thin Layer: Use your fingertips or a cotton swab to apply a thin layer of the gel to the affected area as directed [1.6.3]. Follow dosage instructions carefully; for a 5% ointment, a single application should not exceed 5 grams [1.6.2].
Important Safety Information:
- External Use Only: Do not apply to open wounds, burns, or infected skin unless directed by a doctor [1.7.1].
- Avoid Sensitive Areas: Be careful to avoid contact with eyes. If contact occurs, rinse immediately with water [1.7.1].
- Do Not Overuse: Using too much lignocaine or applying it to large areas of the body can lead to excessive absorption and serious side effects, including dizziness, seizures, or heart problems [1.2.3, 1.4.1].
- Oral Numbness: If using the gel in the mouth or throat, avoid eating, drinking, or chewing gum for at least one hour after use to prevent accidental biting of the tongue or cheeks and to avoid choking [1.7.1].
- Side Effects: Common side effects include temporary redness, stinging, or swelling at the application site [1.7.2]. Serious side effects are rare but can include allergic reactions, changes in heartbeat, or signs of methemoglobinemia (like pale/bluish skin and shortness of breath) [1.7.3]. Seek medical help immediately if you experience severe side effects [1.2.3].
Conclusion
The time it takes for lignocaine gel to work ranges from a few minutes to an hour, depending heavily on where it's applied and the condition of the skin [1.2.7, 1.2.2]. Its effectiveness as a local anesthetic makes it a valuable tool for managing pain from minor skin conditions and preparing for medical procedures [1.6.1]. By understanding the factors that influence its onset and adhering to safety guidelines, users can benefit from its numbing properties while minimizing risks. Always consult with a healthcare provider for proper diagnosis and treatment instructions.
For more detailed information, you can refer to the NHS page on lidocaine skin cream.
