Anabolic steroids (anabolic–androgenic steroids)

Mechanism of action

AAS act primarily by binding the intracellular androgen receptor. This receptor–ligand complex modulates gene transcription in target cells, leading to increased synthesis of proteins involved in muscle growth and increased production of red blood cells. Some effects arise through conversion of testosterone to dihydrotestosterone (DHT) or to estrogens by aromatase; these metabolites have distinct actions on tissues. In addition to genomic effects on gene expression, AAS may produce rapid non‑genomic actions through other signalling pathways.

Pharmacology and formulations

Synthetic AAS differ in chemical structure, potency, and pharmacokinetics. Common formulations include injectable esters (prolonged action), oral 17α‑alkylated compounds (resistant to liver breakdown but with greater risk of hepatic toxicity), and transdermal systems. Some agents are more prone to aromatization to estrogens, while others are more readily reduced to DHT. These differences influence therapeutic choices and adverse effect profiles.

Medical uses

When managed by clinicians, AAS have accepted medical indications. These include replacement therapy for hypogonadism (documented low testosterone), certain forms of delayed puberty in males, some anemias, and the management of wasting and cachexia associated with chronic illnesses such as HIV/AIDS or cancer. Use in medicine aims to restore function or body composition with the lowest effective dose and appropriate monitoring for adverse effects.

Non‑medical use and sporting context

Outside clinical practice, AAS are often used at supratherapeutic doses to increase muscle mass, strength and appearance. Non‑medical patterns of use include "cycling" (periods of use interspersed with abstinence), "stacking" (combining several agents) and escalated dosing. Use for performance enhancement is prohibited by most major sporting organizations and is subject to anti‑doping controls. Laws and penalties for possession, distribution and use vary between jurisdictions.

Health risks and adverse effects

Risks depend on agent, dose and duration. Common harms associated with long‑term or high‑dose exposure include adverse changes in blood lipids (reduced HDL cholesterol and increased LDL cholesterol), hypertension, liver injury (particularly with certain oral agents), acne and hair growth changes. Endocrine effects include suppression of endogenous testosterone production, testicular atrophy and impaired fertility; adolescents risk premature closure of growth plates and stunted adult stature. Women may develop virilization such as deepening of the voice and increased facial hair. Psychological effects including mood changes, aggression and dependence have been reported.

Dependence, withdrawal and clinical management

Some users develop psychological dependence or regular patterns of use despite harm. Withdrawal after cessation can include fatigue, depressed mood and low libido related to suppressed hypothalamic–pituitary–gonadal function. Clinical management of AAS‑related problems includes medical assessment, laboratory monitoring (lipids, liver enzymes, hormone levels), psychological support, and specialist referral when needed. Restoring natural testosterone production may take months; supervised approaches are recommended.

Detection, regulation and public health

Anti‑doping agencies use urine and blood testing to detect prohibited AAS and their metabolites. Detection windows vary by compound and assay sensitivity; forensic and sports laboratories continuously develop methods to identify novel or designer steroids. Public health responses emphasise education, harm reduction, and access to medical care for adverse effects. Regulatory status of AAS differs internationally, with many countries restricting non‑medical distribution.

History and social aspects

Androgens were isolated and synthetic derivatives developed in the early 20th century, with compounds synthesized in the 1930s for medical study and use. Since the mid‑20th century the non‑medical use of AAS has grown in bodybuilding, athletics and some occupational contexts, prompting ethical debates, legal controls and clinical research into long‑term outcomes.

Further reading and resources

• Chemistry and classification of anabolic steroids
• Androgen receptor biology and signalling
• Testosterone: physiology and clinical role
• Protein synthesis and muscle growth mechanisms
• Skeletal muscle structure and adaptation
• Muscle physiology and exercise responses
• Development of male secondary sexual characteristics
• Anabolism in metabolic context
• Etymology of the term "anabolism"
• Clinical guidelines for androgen therapy
• Management of wasting in HIV/AIDS
• Supportive care in cancer‑related cachexia
• Lipid changes and cardiovascular risk with AAS
• Dermatological effects: acne and hair changes
• Blood pressure effects and cardiovascular monitoring
• Liver safety, hepatotoxicity and monitoring
• Doping and regulation in racing and sport
• Bodybuilding culture and patterns of use
• Ethical controversies in performance enhancement
• Anti‑doping rules, testing and legal frameworks