Chemical tinkering with the hydrocortisone molecule has produced drugs such as prednisolone. This suppresses inflammation but has very little effect on the excretion of salt by the kidneys, so it will not cause water retention.
Unfortunately, these are not the only bad effects of corticosteroids. Because they suppress inflammation, which is a valuable part of the body’s fight against disease, they tend to make infections more likely. Viruses and fungi, in particular, are likely to flourish.
If corticosteroids are taken over a long period of time, the adrenal glands’ natural activity is suppressed. Stopping the drug leaves the body without corticosteroids which can lead to collapse in the worst cases. This means that corticosteroids taken by mouth should never be stopped abruptly if they have been taken for more than a few weeks. The glands must be given time to recover their natural level of activity, by gradually reducing the dosage. Even after as little as two weeks, corticosteroids should be withdrawn gradually, by halving the dose each day, to avoid a flare-up of the original problem.
In general, applying corticosteroids locally lie where they are needed) is preferable to taking them by mouth or injecting them, because it reduces the dose needed and thus minimizes side-effects. This means applying the drug in creams or ointments for eczema, inhaling it for asthma, or injecting it directly into an affected joint for rheumatoid arthritis. Some of the drug still gets into the bloodstream however-for example, it can be absorbed through the skin. Children with eczema who are smothered in high-dose corticosteroid cream by their parents can develop Cushing’s Syndrome, although this is now very rare as doctors are more aware of the dangers.
Corticosteroids are valuable weapons in the fight against many diseases, but must always be used with some caution. The doctor’s instructions, as regards the amount and timing of the dose, must be followed exactly.