Newsbeat's guide to... steroids

Dozens of police officers are being investigated over their use of anabolic steroids supplied by criminals, a report has found.

The report, by Transparency International UK, was commissioned by the Association of Chief Police Officers (Acpo) in England and Wales.

It warns that police could be vulnerable if they depend on criminals for their supply of the drugs.

Mike Cunningham, the Chief Constable of Staffordshire, said: "We do our own assessment of corruption threats, one of them is steroid abuse and gym use by officers.

"What that starts off is very often officers going to the gyms, beginning to dabble in steroids, then the relationships they form when they're using steroids become corrupt and corrosive."

What are steroids?

Anabolic steroids are hormones involved in growth, physical development and the function of the reproductive organs and are found naturally in the body.

The drugs are manmade versions of the same or similar hormones.

Steroids come in tablets or are often injected in liquid form.

In the medical profession they're used to boost red blood cell numbers in anaemic patients.

Why are they used?

Some bodybuilders, sports fanatics and athletes use steroids to increase the rate and amount of muscle growth.

Some athletes and bodybuilders take them typically in cycles of weeks or months in patterns called cycling.

Cycling involves taking multiple doses of steroids over a specific period of time, stopping for a period, and starting again.

Taking steroids, training hard and eating a high protein diet will build your body weight up and increase the size of your muscles.

Steroids can also help with faster recovery times after exercise.

Are there any side-effects?

Yes, there can be. They can stunt your growth if you are young.

Heavy, regular use could raise your blood pressure, shrink your testicles and damage your liver, kidneys and heart.

Girls can end up with more body hair, smaller breasts and a deeper voice.

Some people say they feel more aggressive and competitive as well with overuse leading to what's called "roid rage".

Injecting steroids incorrectly can also damage people's veins and sharing needles increases the risk of catching diseases like HIV and hepatitis B and C.

Are steroids legal?

Anabolic steroids are Class C drugs.

They can only be sold by pharmacists with a GP's prescription.

It's legal to possess or import steroids as long as they're for personal use.

It was made illegal to import them for personal use using postal, courier or freight services last year.

Possession or importing with intent to supply is illegal and the maximum sentence for possession for supplying anabolic steroids is 14 years in prison and/or an unlimited fine.

Follow @BBCNewsbeat on Twitter