Im pretty sure this is what I took daily throughout childhood for asthma. Ultimately i developed a goiter which cleared up when we stopped the drops so its defintely not good for daily use. But it kept me off steroids and for the years i took it i had a blessedly symptom free and active childhood. I think it’s worth trying for short periods for persistant colds and I may ask for this again next time I have one. It’s a good alternative to steroids for asthmatics who get symptomatic from colds.