To avoid additives, I had patients make saline themselves, using Kosher or Pickling salt - a simple, pure salt. This cleared up the burning problem, and made kids much more likely to take to regular use of the spray. Some patients did not respond, however, even to the saline made without preservatives. The explanation came only recently from Professor Wilbert M Boek of University Hospital, Utrecht. My clinical experience has borne this out.
Thimerosal There is yet more complexity to the business of additives.
It has been used in small amounts to reduce the chance of bacterial growth since the 1930s. Benzalkonium The preservative Benzalkonium Sodium causes problems with nasal sprays. The drops become effectively addictive, and worse, the nose is always stuffy anytime the drug is not active in the nose. Next, it was discovered that you could get rhinitis medicamentosum just form the Benzalkonium alone, as well as saline with Benzalkonium. So, it wasn't the nasal medication oxymetazoline that was responsible, but the Benzalkonium.