From the FDA Drug Label
For symptomatic treatment of irritated or inflamed mucous membranes of the mouth and pharynx, the usual adult dose is one 15 mL tablespoonful undiluted. For use in the mouth, the solution should be swished around in the mouth and spit out For use in the pharynx, the undiluted solution should be gargled and may be swallowed. This dose should not be administered at intervals of less than three hours, and not more than eight doses should be given in a 24-hour period.
The frequency of prn dosing for viscous lidocaine & aluminum hydroxide-magnesium hydroxide swish and spit for throat pain from vomiting is every 3 hours, with a maximum of 8 doses in a 24-hour period 1.
From the Research
For throat pain from vomiting, viscous lidocaine can be used every 3-4 hours as needed, with a typical dose of 5-15 mL swished in the mouth for 30-60 seconds and then spit out, while aluminum hydroxide-magnesium hydroxide suspension can be used similarly, swished and spit every 4-6 hours as needed. These medications work in different ways: lidocaine provides temporary numbing of the throat by blocking nerve signals, while the antacid suspension coats and soothes irritated tissue while neutralizing stomach acid that may have damaged the throat during vomiting 2. Do not swallow viscous lidocaine as it can cause systemic side effects. For both medications, avoid eating or drinking for 30 minutes after use to maximize effectiveness. If throat pain persists beyond 2-3 days or is accompanied by difficulty swallowing, fever, or visible throat damage, medical evaluation is recommended as this may indicate more serious injury requiring different treatment. Some studies suggest that the frequency of administration can vary, with some institutions administering the mouthwash every 4 hours (36%) or every 6 hours (36%) 2. However, the most effective and safe frequency of administration should be determined on a case-by-case basis, taking into account the severity of symptoms and individual patient needs. It is also important to note that the use of topical oral solutions, such as "magic mouthwash," can vary widely in terms of ingredients and administration schedules, and there is a need to standardize these solutions to fully evaluate their efficacy in managing throat pain and other symptoms 2. In general, the goal of treatment should be to provide effective symptom relief while minimizing the risk of adverse effects and promoting overall quality of life. The use of viscous lidocaine and aluminum hydroxide-magnesium hydroxide suspension can be an effective and safe way to manage throat pain from vomiting, as long as they are used as directed and under the guidance of a healthcare professional. It is also important to consider the potential interactions between these medications and other treatments, as well as any underlying medical conditions that may affect their use 3, 4, 5, 6.