A steroid is a type of organic compound built around a specific molecular structure: four interconnected carbon rings that form a shared backbone. Your body produces dozens of steroids naturally, and they control everything from inflammation to sexual development to salt balance. In medicine, the word “steroid” usually refers to one of two very different types of drugs: corticosteroids, which reduce inflammation, and anabolic steroids, which mimic testosterone. Understanding the difference matters because the two have almost nothing in common beyond their chemistry.
Steroids Your Body Makes Naturally
Your adrenal glands, which sit on top of your kidneys, produce more than 30 different steroids. These fall into three functional categories. Glucocorticoids, the most well-known being cortisol, regulate your stress response, blood sugar, and immune activity. Mineralocorticoids control the balance of sodium and potassium in your blood, which directly affects blood pressure. And androgens, including testosterone, drive muscle development, bone density, and reproductive function.
Your ovaries and testes produce additional steroid hormones: estrogen and progesterone in women, and larger amounts of testosterone in men. Cholesterol, a molecule most people associate with heart health, is actually the raw material your body uses to build all of these steroid hormones. Every steroid in your body starts as cholesterol and gets chemically modified step by step into the specific hormone needed.
Corticosteroids: The Anti-Inflammatory Kind
When most doctors say “steroids,” they mean corticosteroids. These are synthetic drugs designed to mimic cortisol, the hormone your body releases during stress and inflammation. They work by entering your cells and essentially turning down the genes responsible for producing inflammatory signals. The result is a broad, powerful suppression of your immune response, which is why they’re prescribed for conditions like asthma, rheumatoid arthritis, lupus, eczema, and inflammatory bowel disease.
Corticosteroids come in many forms depending on where the inflammation is. Inhalers deliver them directly to the lungs for asthma. Creams and ointments treat skin conditions like eczema and psoriasis. Nasal sprays target allergies. Joint injections reduce localized swelling. And oral pills or intravenous forms treat widespread inflammation throughout the body. The delivery method matters because it determines how much of the drug reaches the rest of your system. An inhaler deposits a small dose locally, while a pill affects your entire body.
Topical Steroid Strength
Topical corticosteroids are ranked on a seven-class potency scale, with Class I being the strongest and Class VII the mildest. Over-the-counter hydrocortisone cream (1% or 2.5%) sits at the bottom of that scale in Class VII. Prescription creams range all the way up to Class I for severe skin conditions. Your doctor chooses the potency based on where on your body the problem is (thinner skin like the face needs milder formulations) and how severe the inflammation is.
Side Effects of Long-Term Use
Short courses of corticosteroids are generally well tolerated. The problems show up with prolonged use, particularly oral or injectable forms that affect your whole body. Weight gain (especially in the face and midsection), thinning skin, elevated blood sugar, weakened bones, and high blood pressure are all common with extended treatment. These side effects happen because the drug mimics cortisol so broadly that it disrupts multiple systems at once.
One of the more serious risks involves your adrenal glands. When you take corticosteroids for weeks or months, your body recognizes the external supply and dials back its own cortisol production. If you stop the medication abruptly, your adrenals can’t pick up the slack fast enough. This can trigger fatigue, nausea, vomiting, muscle pain, weight loss, and in severe cases a dangerous drop in blood pressure called an adrenal crisis. That’s why doctors taper the dose gradually, giving your body time to restart its own hormone production.
Anabolic Steroids: The Muscle-Building Kind
Anabolic-androgenic steroids are synthetic versions of testosterone. “Anabolic” refers to their muscle-building properties, and “androgenic” refers to their ability to promote male characteristics like body hair and a deeper voice. These are the steroids associated with athletic doping scandals and bodybuilding culture, and they are completely different drugs from corticosteroids.
They work by entering muscle cells and binding to androgen receptors. In its resting state, this receptor sits in the cell’s cytoplasm attached to chaperone proteins, doing nothing. When testosterone or a synthetic steroid binds to it, the receptor activates, travels to the cell nucleus, and switches on genes that drive protein synthesis and muscle growth. The result is faster recovery from exercise, increased muscle mass, and greater strength.
Doctors do prescribe anabolic steroids in limited situations, such as delayed puberty in boys or muscle-wasting conditions from diseases like HIV. But the vast majority of anabolic steroid use happens outside medical supervision, and that’s where the health risks become serious.
Health Risks of Anabolic Steroid Misuse
The cardiovascular damage is the most dangerous. Studies using echocardiography and cardiac MRI have found pathological heart enlargement in long-term users, particularly bodybuilders and powerlifters. This isn’t the healthy heart growth that comes from aerobic exercise. It’s a type of thickening that reduces the heart’s ability to pump efficiently and can progress to heart failure. Some users with normal coronary arteries have been diagnosed with scarring of the heart muscle.
Anabolic steroids also distort cholesterol balance, lowering protective HDL cholesterol and raising harmful LDL cholesterol, which increases the risk of coronary artery disease and stroke. The good news is that lipid levels typically return to normal within weeks to months after stopping use.
Other organ damage accumulates with prolonged use. The liver and kidneys bear the burden of processing these drugs, and long-term oral use has been linked to liver scarring and kidney failure. In men, the body responds to the external testosterone by shutting down its own production, leading to shrunken testicles, low sperm counts, and infertility. In women, anabolic steroids can cause permanent voice deepening, menstrual disruption, and other masculinizing effects. Athletes also face a significantly higher risk of tendon ruptures, likely because muscle strength outpaces the connective tissue’s ability to adapt.
Why the Two Types Get Confused
The confusion between corticosteroids and anabolic steroids is one of the most persistent misunderstandings in medicine. A patient prescribed a corticosteroid inhaler for asthma sometimes worries they’re taking the same drugs that get athletes banned from competition. They’re not. Corticosteroids suppress immune activity and reduce swelling. Anabolic steroids build muscle and mimic testosterone. They share a basic molecular skeleton, and they share the word “steroid,” but their effects on the body are fundamentally different.
If your doctor prescribes a “steroid,” it is almost certainly a corticosteroid. Anabolic steroids require specific prescriptions for narrow conditions and are controlled substances in most countries. Knowing which type you’re dealing with changes everything about what to expect, what the risks are, and why the treatment was chosen.