In general, corticosteroids are grouped into four classes, based on chemical structure. Allergic reactions to one member of a class typically indicate an intolerance of all members of the class. This is known as the "Coopman classification", after S. Coopman, who defined this classification in 1989.
The highlighted steroids are often used in the screening of allergies to topical steroids.
There is also a combination preparation (trade name Advair), containing fluticasone propionate and salmeterol xinafoate (a long-acting bronchodilator). It is approved for children over 12 years old.
Clinical and experimental evidence indicates that corticosteroids can cause permanent eye damage by inducing central serous retinopathy (CSR, also known as central serous chorioretinopathy, CSC). A variety of steroid medications, from anti-allergy nasal sprays (Nasonex, Flonase) to topical skin creams, to eye drops (Tobradex), to prednisone have been implicated in the development of CSR.
Corticosteroids have been widely used in treating people with traumatic brain injury. A systematic review identified 20 randomised controlled trials and included 12,303 participants, then compared patients who received corticosteroids with patients who received no treatment. The authors recommended people with traumatic head injury should not be routinely treated with corticosteroids.
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 oxbile. 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, D.H. Peterson and H.C. 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 $0.46 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.
Side effects such as cutaneous addiction with the development of uncomfortable and unsightly dermatoses, can occur with just one 15 g tube of moderate steroid over a period of one year.
Use of corticosteroids has numerous side-effects, some of which may be severe:
Neuropsychiatric: steroid psychosis, and anxiety,depression. Therapeutic doses may cause a feeling of inappropriate well-being ("steroid euphoria"). The neuropsychiatric effects are partly mediated by sensitization of the body to the actions of adrenaline. Therapeutically, the bulk of corticosteroid dose is given in the morning to mimic the body's diurnal rhythm; if given at night, the feeling of being energized will interfere with sleep. An extensive review is provided by Flores and Gumina.
Cardiovascular: Corticosteroids can cause sodium retention through a direct action on the kidney, in a manner analogous to the mineralocorticoid aldosterone. This can result in fluid retention and hypertension.
Metabolic: Corticosteroids cause a movement of body fat to the face and torso, resulting respectively in "moon face" and "buffalo hump". and away from the limbs. Due to the diversion of amino-acids to glucose, they are considered anti-anabolic, and long term therapy can cause muscle wasting 
Gastro-intestinal: While the evidence for corticosteroids causing peptic ulceration is relatively poor except for high doses taken for over a month, the majority of doctors as of 2010[update] still believe this is the case, and would consider protective prophylactic measures.
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^Marker, Russell E.; Wagner, R. B.; Ulshafer, Paul R.; Wittbecker, Emerson L.; Goldsmith, Dale P. J.; Ruof, Clarence H. (1947). "Steroidal Sapogenins". J. Am. Chem. Soc.69 (9): 2167–2230. doi:10.1021/ja01201a032. PMID20262743.
^Peterson D.H., Murray, H.C. (1952). "Microbiological Oxygenation of Steroids at Carbon 11". J. Am. Chem. Soc.74 (7): 1871–2. doi:10.1021/ja01127a531.
^Julian, Percy L., Cole, John Wayne, Meyer, Edwin W., and Karpel, William J. (1956) "Preparation of Cortisone". U. S. Patent 2,752,339
^C R Swinburn, J M Wakefield, S P Newman, and P W Jones Evidence of prednisolone induced mood change ('steroid euphoria') in patients with chronic obstructive airways disease" Br J Clin Pharmacol 1988 December; 26(6) 709–713. URL: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1386585/
^Pecora PG, Kaplan B (1996). "Corticosteroids and ulcers: is there an association?". Ann Pharmacother30 (7–8): 870–2. PMID8826575.
^Martínek J, Hlavova K, Zavada F, et al. (June 2010). ""A surviving myth" — corticosteroids are still considered ulcerogenic by a majority of physicians". Scand J Gastroenterol45 (10): 1156–61. doi:10.3109/00365521.2010.497935. PMID20569095.
^Fukushima C, Matsuse H, Tomari S, Obase Y, Miyazaki Y, Shimoda T, Kohno S. Oral candidiasis associated with inhaled corticosteroid use: comparison of fluticasone and beclomethasone.Ann Allergy Asthma Immunol. 2003 Jun;90(6):646-51. http://www.ncbi.nlm.nih.gov/pubmed/12839324
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