Methylxanthines are administered orally or intravenously. Before the inhalers became popular, methylxanthines were the mainstay of treatment of asthma. Theophylline can also act as a mild diuretic, causing an increase in urination. For asthma that is difficult to control, methylxanthines can still play an important role. Dosage levels of theophyline or aminophylline are closely monitored.
Excessive levels can lead to nausea, vomiting, heart rhythm problems, and even seizures.
In certain medical conditions, such as heart failure or cirrhosis, dosages of methylxanthines are lowered to avoid excessive blood levels. Corticosteroids are given orally for severe asthma unresponsive to other medications. Unfortunately, high doses of corticosteroids over long periods can have serious side effects, including osteoporosis, bone fractures, diabetes mellitus, high blood pressure, thinning of the skin and easy bruising, insomnia, emotional changes, and weight gain. Expectorants help thin airway mucus, making it easier to clear the mucus by coughing. Potassium iodide is commonly used but has the potential side-effects of acne, increased salivation, hives, and thyroid problems.