How Do Anabolic Steroids Work?


Anabolic steroids (also known as anabolic-androgenic steroids, AASs) are a class of drugs used to treat anemia (low red blood cell count) and symptoms of hypogonadism (a condition in which the body does not produce enough natural testosterone) in males and metastatic breast cancer in females. Steroids are chemicals, often hormones, that the body makes naturally to help organs, tissues, and cells perform routine activities. The two main types of steroids are corticosteroids and anabolic steroids. Anabolic steroids are synthetic hormones (man-made versions of testosterone) that help the body in the growth and repair of muscle tissues. They imitate the male sex hormone, testosterone and are often prescribed to boys with delayed puberty, men with low testosterone levels (an average male has approximately 300-1,000 ng/dL), and people who lose muscle mass because of cancer, AIDS, and other health conditions.

Anabolic steroids are also known as "performance-enhancing drugs" and are often misused. People illegally use anabolic steroids to increase lean muscle mass, reduce fat, and speed up recovery from injury. Some athletes, weightlifters, and bodybuilders take them regularly to improve their physical performance and build up their bodies. The misuse of anabolic steroids can cause long-term side effects including cardiovascular complications, liver disease, reproductive organ damage, and severe mood swings.

AASs are prescription-only medicines that are sometimes taken without medical advice to increase muscle mass and improve athletic performance. They are available as a tablet to be taken orally with or without food once a day or three or four times a day. 

AASs work in the following ways:

  • They work by increasing the amount of the hormone “erythropoietin” involved in the production of red blood cells.
  • When used to treat breast cancer, they work by blocking the release of estrogen to stop or slow down the growth of breast cancer.
  • They imitate the properties of the naturally occurring hormone “testosterone” and activates the body’s testosterone receptors.
  • This stimulation of receptors leads to a domino effect of metabolic reactions which instructs the body to increase muscle tissue production of testosterone.
  • Testosterone affects the body in two ways:
    • Anabolic: maintains bone density, supports muscle growth, and speeds up recovery from injury.
    • Androgenic (also known as masculinizing): develops and maintains male characteristics (such as the penis, testicles, muscle mass, deep voice, and facial hair).


Anabolic steroids are used for various health and athletic purposes, including:

  • Anemia caused by deficient red cell production which includes:
  • Hypogonadism in males because of:
    • Bilateral testicular torsion (a rare condition with a majority of cases occurring in neonates)
    • Testicular failure due to cryptorchidism (a condition in which one or both testes fail to descend from the abdomen into the scrotum)
    • Orchitis (inflammation of one or both testicles)
    • Vanishing testis syndrome (a developmental anomaly characterized by the absence of one or both testicles with partial or complete absence of testicular tissue)
    • Orchidectomy (a surgical procedure in which one or both testicles are removed)
  • Hypogonadotropic hypogonadism because of:
  • Delayed puberty in male children
  • Metastatic breast cancer in females
  • Prevention of postpartum breast engorgement
  • Prevention and treatment of muscle wasting in HIV patients


Some of the common side effects include:

  • Diarrhea
  • Nausea
  • Vomiting
  • Muscle cramps
  • Insomnia (trouble falling and/or staying asleep)
  • Acne
  • Edema (swelling)

Other rare side effects include:

  • Males
    • Bladder irritability
    • Impotency (inability to get and keep a firm erection)
    • Priapism (a condition that causes persistent and sometimes painful erections)
    • Epididymitis (swelling or pain in the back of the testicle in the coiled tube [epididymis] that stores and carries sperm)
    • Gynecomastia (an enlargement or swelling of breast tissue in males)
    • Prepubertal: phallic enlargement and increased frequency of erections
    • Postpubertal: inhibition of testicular function, testicular atrophy (shrinking of testicles), and oligospermia (low sperm count) and decrease in seminal volume
  • Females
    • Alopecia (a condition that causes hair to fall out in small patches)
    • Virilism (a condition in which women develop male-pattern hair growth and other masculine physical traits)
    • Menstrual irregularities
    • Male-like voice
    • Breast soreness
  • Increased or decreased libido (desire for sexual activity)
  • Hirsutism (a condition in which a woman develops excessive hair growth)
  • Electrolyte and water retention
  • Mood changes
  • Anxiety
  • Depression

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.


Generic and brand names of anabolic steroids include:


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