Anabolic steroids are sometimes used by body-builders, athletes and sports fanatics to help their muscles grow. But did you know they can stunt your growth and shrink your testicles? And that's just for starters.
What is it?
Anabolic steroids are a group of hormones found naturally in our bodies. They are involved in growth, physical development and the function of the reproductive organs.
The drugs are manmade versions of the same or similar hormones. They come as pills or capsules. They are usually taken by mouth, but can be injected. Their medical use is limited to boosting red blood cell numbers in anaemic patients.
Bodybuilders, sports fanatics and athletes use them to increase the rate and amount of muscle growth.
Anabolic steroids aren't the same as the steroids used to treat eczema and asthma - these are corticosteroids.
How does it make you feel?
Taking anabolic steroids, training hard and eating a high protein diet is likely to build your body weight up and increase the size of your muscles. Some people say they feel more aggressive and competitive as well.
Occasionally people get 'roid rage' where they are violent and sexually abusive. No-one knows if this is down to the drugs or the people though.
What are the health effects?
Anabolics can stunt your growth if you are young. Heavy, regular use could shrink your testicles, raise your blood pressure and damage your liver, kidneys and heart. Girls can end up with more body hair, smaller breasts and a deeper voice. Like many other substances, they are also addictive.
Anabolic steroids are prescription only drugs. Possessing them for personal use is not illegal. But, counterfeit steroids that are quite readily available over the internet are Class C drugs. The maximum sentence for possession for supplying anabolic steroids is 14 years in prison and/or an unlimited fine. Drug testing has outlawed the use of steroids in sport.
BBC Advice factfiles are here to help young people with a broad range of issues. They're based on advice from medical professionals, government bodies, charities and other relevant groups. Follow the links for more advice from these organisations.