Baby Shampoo Used to Treat Chronic Sinusitis

Yes... It's absolutely true! There's even research on this (limited).

The mixture ratio is 1/2 teaspoon of Johnsons No-Tears Baby Shampoo in 8 ounces of saltwater rinsed into the nose using a sinus rinse bottle can help with chronic sinusitis, especially when there's a lot of crusting present and to which all other therapies have failed to resolve.

The shampoo appears to work via several mechanisms theoretically:

1) It is directly toxic to germs
2) The soap action helps break apart crusting (similarly to the way detergent gets rid of mud from a kid's shirt in the washer)
3) The soap also helps break down and remove biofilms in the sinus cavities which tends to resist antibiotics and cause recurrent sinus infections (just like dishwasher fluid gets filmy food residue off plates)

For saline flushes, the NeilMed Sinus Rinse bottle is recommended for two reasons.

The black cap of the bottle is about 1 teaspoon... and the bottle itself is 8 ounces.

So, for the particularly difficult chronic sinusitis infection patient who has tons of crusting for which all other treatments have failed, the saltwater is made up as per routine using the NeilMed Sinus Rinse bottle, but than to also add 1/2 capful of the Johnson's No-Tears Baby Shampoo as well before use.

They are to flush their nose twice a day for a few weeks.

Reference:
Baby shampoo nasal irrigations for the symptomatic post-functional endoscopic sinus surgery patient. Am J Rhinol. 2008 Jan-Feb;22(1):34-7.