Steroids have a wide range of proven medical benefits, from controlling dangerous inflammation to rebuilding muscle in people with wasting diseases. The term “steroids” actually covers two very different classes of drugs: corticosteroids, which suppress inflammation and immune activity, and anabolic steroids, which promote muscle growth and tissue repair. Both have legitimate medical uses, and both produce measurable physical changes that explain why they remain essential tools in modern medicine.
Two Types of Steroids, Two Different Jobs
Corticosteroids are synthetic versions of cortisol, a hormone your adrenal glands produce naturally. They work by dialing down your immune system’s activity and reducing inflammation throughout the body. Doctors prescribe them for conditions like asthma, rheumatoid arthritis, lupus, inflammatory bowel disease, severe allergies, and skin disorders like eczema and psoriasis. They also play a critical role in preventing organ rejection after a transplant.
Anabolic steroids are synthetic versions of testosterone. They promote protein synthesis in muscle tissue, increase bone density, and stimulate red blood cell production. In medical settings, they’re used to treat hormone deficiencies, muscle-wasting conditions, certain types of anemia, and delayed puberty. Outside of medicine, athletes and bodybuilders use them to enhance strength and physique, though this comes with significant health risks.
Controlling Inflammation and Autoimmune Flares
The primary benefit of corticosteroids is their ability to shut down runaway inflammation quickly. They work at the cellular level by blocking your body’s production of inflammatory signaling molecules. This is why a corticosteroid injection into a swollen joint can bring relief within days, and why an inhaled corticosteroid can keep asthma symptoms under control for months.
For autoimmune diseases, where the immune system mistakenly attacks the body’s own tissues, corticosteroids can be the difference between a manageable condition and a medical emergency. In a clinical trial of low-dose prednisone for rheumatoid arthritis, 73% of patients on placebo had to withdraw from the study because their symptoms worsened, compared to only 23% of those taking prednisone. Patients on prednisone maintained stable levels of physical function, pain, and fatigue over 24 weeks, while the placebo group deteriorated across every measure.
Corticosteroids come in many forms tailored to specific problems. Oral tablets treat systemic conditions like lupus. Inhalers and nasal sprays target airway inflammation. Eye drops reduce swelling from conditions like uveitis. Topical creams treat skin conditions, with studies showing significant improvement in 13% to 100% of eczema patients after one to twelve weeks of treatment, depending on severity and the specific steroid used. Injections deliver the drug directly to inflamed joints or tendons.
Replacing Missing Hormones
Some people need steroids simply because their bodies don’t make enough. Addison’s disease, a rare condition where the adrenal glands fail, requires lifelong corticosteroid replacement to maintain normal body function. Without it, patients face dangerous drops in blood pressure, blood sugar, and sodium levels.
Similarly, men with clinically low testosterone levels (hypogonadism) receive anabolic steroid therapy to restore normal hormone function. This can improve energy, mood, sexual function, muscle mass, and bone strength. The goal in both cases isn’t enhancement but normalization, bringing hormone levels back to where they should be.
Building and Preserving Muscle
Anabolic steroids are powerful drivers of muscle growth. In the landmark 1996 study by Bhasin and colleagues, men who received testosterone injections without exercising gained more muscle than men who exercised without testosterone. Those who combined testosterone with resistance training saw the largest gains, with a significant additive effect on both muscle thickness and strength. A more recent meta-analysis of studies on healthy exercising adults found that anabolic steroid use improved strength by an average of 52% compared to non-users, alongside measurable improvements in body composition.
At the cellular level, anabolic steroids don’t just make existing muscle fibers bigger. Research on strength-trained athletes found that steroid users had larger muscle fibers across all types, more nuclei within each fiber, and a higher frequency of fibers expressing developmental proteins, which are markers of newly forming muscle tissue. The key mechanism appears to be activation of satellite cells, specialized stem cells that sit on the surface of muscle fibers. When activated, these cells fuse into existing fibers or form entirely new ones, driving growth through both enlargement (hypertrophy) and the creation of new muscle fibers.
This muscle-building capacity has direct medical applications. In people with HIV-related wasting, a condition where patients lose dangerous amounts of lean body mass, anabolic steroid treatment produced an average gain of 1.3 kilograms of lean tissue according to a Cochrane systematic review of eleven studies. Men specifically gained an average of 1.5 kilograms. While these numbers may sound modest, for patients experiencing progressive muscle loss that threatens their ability to function and survive, regaining over a kilogram of lean mass is clinically meaningful.
Stimulating Red Blood Cell Production
Anabolic steroids boost the production of red blood cells, the oxygen carriers in your blood. In one controlled study, steroid administration increased blood hematocrit (the percentage of blood volume occupied by red cells) by 9.6% in the treatment group, with no change in controls. This effect is driven by a genuine increase in red blood cell count, not just a change in cell size.
This property made anabolic steroids one of the earlier treatments for certain types of anemia, particularly in patients whose bone marrow wasn’t producing enough red blood cells on its own. While newer drugs have largely replaced steroids for anemia treatment, the erythropoietic effect remains relevant. It’s also one reason athletes misuse these drugs: more red blood cells means more oxygen delivery to working muscles, which translates to better endurance.
Supporting Bone Health
Certain anabolic therapies help rebuild bone in patients with osteoporosis. In clinical trials, patients treated with bone-building agents saw lumbar spine bone mineral density increase by 9.7% compared to placebo. Hip bone density increased by 3.6% to 5.1%, and femoral neck density by 2.6% to 2.8%. For someone at risk of fractures from brittle bones, these improvements meaningfully reduce the chance of a break that could lead to disability or death, particularly in older adults.
This is somewhat ironic given that corticosteroids, the other class of steroids, are a well-known cause of bone loss when used long-term. The two types of steroids have opposite effects on bone: anabolic steroids build it up, while prolonged corticosteroid use breaks it down.
The Benefits Come With Real Tradeoffs
Every benefit of steroids exists on a spectrum with potential harm. Corticosteroids, even at low doses, can cause weight gain, elevated blood sugar, mood changes, and thinning skin. At higher doses or over longer periods, risks expand to include osteoporosis, high blood pressure, cataracts, and increased susceptibility to infections, since the same immune suppression that treats autoimmune disease also weakens your defense against bacteria and viruses.
Anabolic steroids carry a different set of risks. The same testosterone-like effects that build muscle also affect the heart, liver, hormonal balance, and mood. Long-term use is associated with cardiovascular damage, liver problems, hormonal disruption (including infertility and testicular shrinkage in men), acne, and psychological effects ranging from irritability to aggression. In women, anabolic steroids can cause irreversible masculinizing effects like voice deepening and facial hair growth.
The medical benefits of both types of steroids are well established and, in many conditions, irreplaceable. But those benefits depend on using the right type, at the right dose, for the right duration, under medical supervision. The further steroid use strays from that framework, the more the risk-to-benefit ratio tilts toward harm.