I have been having breathing problems for a few years now. I have no wheeze at all, but I have trouble getting a deep breath. I have tried a variety of asthma medicines and none work at all for me. The only medicine that does work for me is pseudoephedrine . I do not want to a make a habit of taking it though, as I find it hard on the nervous system . As an aside, I am treated for hypothyroidism and take 137 mcg of synthroid daily. I was wondering if this breathing issue could result from insufficient thyroid hormones. I have a feeling the effect pseudoephedrine has on my breathing is a result of its effect on my nervous system rather than its effect as a decongestant. Could it be that pseudoephedrine stimulates my thyroid and hence my respiratory rate is increased? It s been a long, hard battle with this and I would appreciate insightful feedback. After dealing with this for years, I am happy to know something works. Now I just need to know why it works so I can get on a safer medication.