What is the recommended duration of use for viscous (lidocaine)?

Recommended Duration of Use for Viscous Lidocaine

Viscous lidocaine should not be used for more than 7 days without consulting a doctor, as prolonged use increases the risk of toxicity and adverse effects. 1

Administration Guidelines

• Viscous lidocaine should be used for short-term relief of painful oral conditions, with careful attention to duration of use 1
• The FDA recommends discontinuing use and consulting a doctor if symptoms persist for more than 7 days or if they clear up and occur again within a few days 1
• For painful oral procedures, the optimal time interval for effectiveness is between 3-8 minutes after application, with maximal hypoalgesia reached after 4-5 minutes 2
• The hypoalgesic effect of topical lidocaine typically lasts until approximately 14 minutes after application 2

Safety Considerations

• Frequent use of viscous lidocaine can lead to toxicity, as documented in case reports where excessive use (>240 ml per day) resulted in toxic serum lidocaine levels of 6.7 μg/ml 3
• Toxic symptoms can persist even when serum lidocaine concentration falls below toxic levels, suggesting metabolites may contribute to toxicity 3
• Signs of lidocaine toxicity include perioral tingling, tinnitus, light-headedness, restlessness, and in severe cases, cardiovascular and neurological complications 4
• For external use products, rare cases of serious burns have been reported, and patients should avoid bandaging or applying local heat to the area 1

Monitoring and Precautions

• Patients should be monitored for signs of toxicity, especially with frequent use 3
• Discontinue use if redness, irritation, or signs of skin injury (pain, swelling, blistering) develop 1
• Viscous lidocaine should not be used on large areas of the body or on cut, irritated, or swollen skin 1
• Contact with eyes and mucous membranes should be avoided when using topical formulations 1

Special Populations

• For pregnant or breastfeeding patients, consultation with a healthcare professional is required before use 1
• Keep out of reach of children; if swallowed, immediate medical help or contact with a Poison Control Center is necessary 1

Clinical Applications

• For painful infectious mouth conditions in children, 2% viscous lidocaine has been studied for improving oral intake, though definitive evidence of efficacy is still being established 5
• For trigeminal neuralgia with oral pain, 8% lidocaine applied to oral mucosa has shown prompt analgesia without serious side effects 6
• When used for postoperative pain management, intravenous lidocaine infusions should not generally exceed 24 hours 4

Dosing Considerations

• For intravenous administration, the American Society of Anesthesiologists recommends calculating the dose using ideal body weight rather than actual body weight 7
• For topical application, repeated applications of lidocaine spray (beyond 30 mg) have not shown additional hypoalgesic effect 2