“The Ghana Hospital used 1.5%, so you could dilute 3% hydrogen peroxide with distilled water 50-50 and make it go farther or use the 3%. Do not swallow. Just gargle for 30-60 seconds or more and spit out.”

https://www.georgekramermd.com/hydrogen-peroxide-gargling-nasal-rinses-may-prevent-viral-infection/