If the usage of systemic steroid for allergy treatment is continued for a long duration or is repeated frequently, it may lead to some severe and long-term side-effects. Thus, it is always recommended to take the minimum possible dosage of steroid for treating allergy and for a short duration. Taking steroids on the alternate days instead of daily, keeping the overall dosage same can help in preventing some long-term side-effects of steroids in allergy treatment. Common long-term side-effects of steroids are high blood pressure, glaucoma , obesity , cataracts , heart disease, myopathy, acid reflux etc. Some of these side-effects can go away gradually but others may become permanent.
Steroids killed nine-year-old Lexie McConnell after only five and a half weeks. In August 1993, Lexie was diagnosed as having toxoplasmosis. The consultant put her on 80 mg per day of prednisolone. Immediately, she suffered severe side effects, huge weight gain , terrible pains, holes in her tongue and black stools. After nearly a month, at her parents' pleading, the doctors quickly lowered the dosage to 60 mg, 40 mg, 20 mg. In excruciating pain, Lexie was taken to a hospital, where it was discovered she'd contracted chickenpox. Four days later, she died. A few years later, another eye specialist declared that a simple course of antibiotics could have cleared up her infection. The above excerpt is from Ursula Kelly's site