AASs are synthetic versions of the primary male hormone, testosterone. They affect many parts of the body, including the muscles, bones, hair follicles, liver, kidneys, blood, immune system, reproductive system and the central nervous system.

During puberty, increases in testosterone levels enable the development of characteristics such as facial and body hair growth, increased height and muscle mass, a deepening voice, and the sex drive.

Testosterone can also contribute to competitiveness, self-esteem, and aggressiveness.

How do people use them?

Continuous use of AASs can lead to problems such as tolerance. They may even cause the body to stop producing its own testosterone.

Some people use AASs continuously, but others try to minimize their possible adverse effects through different patternsTrusted Source of use.

Cycling: The person takes AASs in cycles of 6 to 12 weeksTrusted Source (known as the “on” period), followed by 4 weeks to several months off.

Stacking: Users combine severalTrusted Source different types of steroids or incorporate other supplements in an attempt to maximize the effectiveness of the steroids. This is called “stacking.”

Pyramiding: Some users gradually increaseTrusted Source the dose to a peak, then reduce the amount.

However, there is no evidence that these methods reduce the risks.

There are up to 32 types of anabolic steroid listed on commercial websites.

Some have only medicinal uses, such as Nebido. Anadrol is an example of a steroid with both medicinal and performance uses.

Others, such as anadur, have no therapeutic use, but athletes use them.

People choose different types for different purposes:

• bulking steroids for building muscle
• performance steroids for strength and endurance
• cutting steroids for burning fat

Other reasons for use include healing and recovery and enhancement of metabolism.

For both medical and illegal purposes, AASs can be taken:

• by mouth
• as pellets implanted under the skin
• by injection
• through the skin as a cream or gel

Oral forms are taken by mouth. They include:

• Fluoxymesterone (Halotestin), or “Halo”
• Mesterolone (Proviron)
• Methandienone (Dianabol), or “Dbol”
• Methyltestosterone (Virilon)
• Mibolerone (Cheque)
• Oxandrolone (Anavar, Oxandrin), or “Var”
• Oxymetholone (Anadrol), or “Drol”
• Stanozolol (Winstrol), or “Winny”

Injectable forms include:

• Boldenone undecylenate (Equipoise), or “EQ”
• Methenolone enanthate (Primobolan), or “Primo”
• Nandrolone decanoate (Deca Durabolin), or “Deca”
• Nandrolone phenpropionate (Durabolin), or “NPP”
• Testosterone cypionate (Depotest)
• Testosterone enanthate (Andro-Estro)
• Testosterone propionate (Testex)
• Trenbolone acetate (Finajet), or “Tren”

AASs travel through the bloodstream to the muscle tissue, where they bind to an androgen receptor. The drug can subsequently interact with the cell’s DNA and stimulate the protein synthesis process that promotes cell growth.

Some types of steroid are commonly used for medical treatment. For example, corticosteroids can help people with asthma to breathe during an attack.

Testosterone is also prescribed for a number of hormone-related conditions, such as hypogonadism.

However, AASs are not commonly prescribedTrusted Source as a treatment.

In the U.S., an AAS is a schedule III controlled substance available only by prescription. The use of these drugs is only legal when prescribed by a medical provider.

Medical conditions they are used to treat include:

• delayed puberty
• conditions that lead to muscle lossTrusted Source, such as cancer and stage 3 HIV, or AIDS

Testosterone and several of its esters, as well as methyltestosterone, nandrolone decanoate, and oxandrolone, are the main anabolic-androgenic steroids currently prescribed in the U.S.

Non-medical use of steroids is not permitted in the U.S. Under the Controlled Substance Act, unlawful possession and distribution are subject to federal and state laws.

As it is not legal for athletic purposes, there is no legal control over the quality or use of drugs sold for this purpose.

Illegal steroids are obtained through the internet and through informal dealers, like other illegal drugs. However, they may also be available through unscrupulous pharmacists, doctors, and veterinarians.

“Designer” steroids are sometimes produced to enable athletes to pass doping tests. Their composition and use are entirely unregulated, adding to the hazards they pose.

Athletes often consumeTrusted Source steroids on a trial-and-error basis, using information gained from other athletes, coaches, websites or gym “gurus.” As a result, they do not have access to medical information and support that can keep them safe while using these drugs.

The adverse effects of AAS use depend on the product, the age and sex of the user, how much they use, and for how long.

Legally prescribed normal-dose anabolic steroids may have the following side effects:

• acne
• fluid retention
• difficulty or pain when urinating
• enlarged male breasts, known as gynecomastia
• increased red cell count
• lower levels of “good” HDL cholesterol and higher levels of “bad” LDL cholesterol
• hair growth or loss
• low sperm count and infertility
• changes in libido

Users will attend follow-up appointments and take periodic blood tests to monitor for unwanted effects.

Non-medical use of steroids can involve quantities from 10 to 100 timesTrusted Source the amount used for medical purposes.

Incorrect use of steroids can lead to an increased risk of:

• cardiovascular problems
• sudden cardiac deathTrusted Source and myocardial infarction
• liver problems, including tumors and other types of damage
• tendon rupture, due to the degeneration of collagen
• osteoporosis and bone loss, as steroid use affects the metabolism of calcium and vitamin D

In adolescents, it can result inTrusted Source:

• permanently stunted growth

In men, there may be:

• shrinking testicles
• sterility
• enlarged breasts

Women may experience:

• changes to the menstrual cycle
• deepening of the voice
• lengthening of the clitoris
• increased facial and body hair
• shrinking breasts
• increased sex drive

Some of these changes may be permanent, even after stopping use.

There is also a risk of:

• liver damage
• aggression and feelings of hostility
• mood and anxiety disorders
• reckless behavior
• psychological dependence and addiction

People who suddenly discontinue AAS after using them for a long time may experience withdrawal symptoms, including severe depression.