What’s the difference between the steroids in asthma inhalers and the ones jocks use?

Dear Cecil: It’s a miracle! No, I don’t have stigmata, I haven’t tasted a Circus Peanut and enjoyed it, and I haven’t heard Steve Miller apologize for ripping off other artists. What has happened is that I’ve found relief for my asthma in a medication known as a steroid (Azmacort). I assume it’s not the same kind of steroid that pumps up men and women with low self-esteem or athletes with no conscience. But what’s the difference? Why am I being told there are no “side effects”? This sounds too good to be true. M. Kelly, Lansing, Michigan

Cecil replies:

I don’t know about “no side effects.” Do they not count blindness these days? Not that that’s likely with careful use of steroid asthma inhalers. But if the message you heard was that inhalers are risk-free, you heard wrong.

Steroids are lot like the Internet — versatile, dangerous in the wrong hands, and seemingly impossible to describe in coherent English. A typical encyclopedia account begins by informing us that steroids are “any of a class of natural or synthetic organic chemical compounds characterized by a molecular structure of 17 carbon atoms arranged in four rings.” Helpful, eh? But eventually we get the picture: Steroids are an important type of hormone, the chemicals by which the body regulates growth and other functions. Sex hormones, bile acids, vitamin D — they’re all steroids. Ordinarily the body manufactures steroid hormones naturally (out of cholesterol, interestingly). For good reasons and bad, though, people sometimes hot-wire the glandular machinery, dosing themselves with ‘roids to get bigger muscles or, in your case, to continue breathing. The results are often dramatic. But over the long term, in some cases, the system fries.

You’re right that the steroids in your inhaler aren’t the same as the ones used by bodybuilders. All steroids are chemically similar (17 carbon atoms in four rings, remember?), but because of differences in the odd atom here and there they have widely varying effects. Anabolic (tissue-building) steroids, the kind some bodybuilders and athletes use, are basically synthetic testosterone. The glucocorticoids used in inhalers, on the other hand, are of a type produced by the adrenal cortex. High doses of glucocorticoids — much higher than the body normally produces — prevent the inflammation that causes asthma. But when taken in pill form they also cause severe side effects, including suppression of the adrenal gland, cataracts, and osteoporosis.

Inhaled steroids, which became popular in the early 1990s, were thought to be safer than the pill kind because they acted directly on the lungs and weren’t spread throughout the body. Today they’re the mainstay of asthma therapy. Studies have shown they greatly reduce the risk of hospitalization or death due to asthma. But in 1997 a Canadian study of 50,000 elderly found that long-term (greater than three months) high-dose use of steroid inhalers substantially increased the risk of glaucoma. Another study of 3,600 folks found inhaled steroids increased the chances of cataracts. Some have disputed these results, and I don’t mean to scare people off. Steroids clearly do control asthma. But I’d definitely sit down with my doctor and discuss the risks. At a minimum I’d want periodic eye exams. These are powerful drugs, and while asthma is certainly a serious problem, so is going blind.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.