Studies on corticosteroids tend to lean toward the extreme use, rather than the average use. For example, some studies look at corticosteroids for extreme and rarer cases of eczema. This makes it harder to research what long-term studies are out there on steroid use. To complicate things further, corticosteroids can be oral, topical, injected, or inhaled, and this dramatically changes the benefits and risks, and in turn the short-term and long-term effects. Speak with your doctor and pharmacist on what, if any, long-term studies out there are relevant to your own medical treatment.
Corticosteroids have been used as drug treatment for some time. Lewis Sarett of Merck & Co. was the first to synthesize cortisone, using a complicated 36-step process that started with deoxycholic acid, which was extracted from ox bile .  The low efficiency of converting deoxycholic acid into cortisone led to a cost of US $200 per gram. Russell Marker , at Syntex , discovered a much cheaper and more convenient starting material, diosgenin from wild Mexican yams . His conversion of diosgenin into progesterone by a four-step process now known as Marker degradation was an important step in mass production of all steroidal hormones, including cortisone and chemicals used in hormonal contraception .  In 1952, . Peterson and . Murray of Upjohn developed a process that used Rhizopus mold to oxidize progesterone into a compound that was readily converted to cortisone.  The ability to cheaply synthesize large quantities of cortisone from the diosgenin in yams resulted in a rapid drop in price to US $6 per gram, falling to $ per gram by 1980. Percy Julian's research also aided progress in the field.  The exact nature of cortisone's anti-inflammatory action remained a mystery for years after, however, until the leukocyte adhesion cascade and the role of phospholipase A2 in the production of prostaglandins and leukotrienes was fully understood in the early 1980s.
Use of QVAR with a spacer device in children less than 5 years of age is not recommended. In vitro dose characterization studies were performed with QVAR 40 mcg/actuation with the OptiChamber and AeroChamber Plus ® spacer utilizing inspiratory flows representative of children under 5 years old. These studies indicated that the amount of medication delivered through the spacing device decreased rapidly with increasing wait times of 5 to 10 seconds as shown in Table 2. If QVAR is used with a spacer device, it is important to inhale immediately.