A trial of 3% saline nasal irrigation for the common cold https://www.nature.com/articles/s41598-018-37703-3 Nasal irrigation with a 3% saline solution eliminates a large proportion of the viruses and significantly shorten the duration of cold + flu symptoms https://www.dailymail.co.uk/health/article-15411919/science-backed-hack-cure-cold-flu-nasal-rinse.html A cold is 2 days shorter