The number of young men using steroids in London is rising on a "regular basis" a drugs charity has warned.
South Westminster Drug and Alcohol Service said an increasing number of young male clients were seeking support for anabolic steroid use.
Home Office figures show 60,000 people used steroids in the UK in 2014.
But the National Institute for Health and Care Excellence said it was the "tip of the iceberg" and advised gyms to supply sharps bins for needles.
Roy Jones, from the South Westminster service, said: "Our numbers are increasing on a regular basis.
"I've been working with steroid users for 16 years and when I first started, the guys taking them were body builders in their 30s.
"Now the average age I see is 23."
According to Professor Gillian Leng, deputy chief executive of the National Institute for Health and Care Excellence (NICE), there is a worrying trend of young professionals turning to the drugs.
She said: "It's fair to say it is becoming a much more normal thing to do among some groups of young men who are concerned about the way they look...injecting steroids has become a solution."
Although government figures suggest 60,000 people used steroids in 2014, professional bodies believe the figure is much higher, as only those ending up in police custody are recorded in the statistics.
What are anabolic steroids?
- Class C drugs that can be injected or taken as tablets
- There are between 60 and 100 different types and though it is illegal to sell or distribute them, using them is not against the law
- Steroids can enhance physical performance and stimulate muscle growth but potential side effects range from acne and hair loss to depression, liver and heart problems
Professor Leng said: "I think it is inevitable that the number is a lot higher.
"From the epidemiology (the data) we have about the kind of people who use steroids - it's a group that's not all going to appear in custody so that figure is bound to be the tip of the iceberg - it might be three times that number."
A 25-year-old, who works in the City of London and asked to remain anonymous, told BBC London he had taken steroids for two years.
He said he bought them from a dealer at his local gym and he knows many others who do the same.
"I started taking them because I felt I couldn't get any bigger training naturally," he said. "It was the next step for me."
"There's immense pressure to look good - it's part of the culture we live in, we all want that big figure."
Easygym have installed sharps bins in all their gyms, while Fitness First, Virgin Active and David Lloyd said some of their clubs also have them.
All the gyms said they had a zero tolerance approach to steroids and the bins were a health and safety measure for diabetic members and the disposal of razors.
The Department of Health said it had "given local areas the power and the funding to tackle public health issues like this".
Despite the increased awareness, Matthew Dear, 17, from Southend, died after an adverse reaction to steroids.
His mother Tina, who runs the Matthew Dear Foundation, which was set up to warn people about the dangers of steroid use, said: "When we lost Matthew six years ago, people thought it was a problem that wasn't going to boil over.
"We are now at that point where it is boiling over and somebody needs to take ownership."
Rolandas Malinauskas, from east London, is a natural bodybuilder - which means strictly no steroids.
The former British Champion said many young men did not consider the dangers of the drugs.
"In the long term, you do not win with steroids - they create a mirage," he said. "You can build muscle naturally but it takes time and dedication. Its all about precision, training and diet."