Synthol is made up of 85% oil, lidocaine (a numbing agent), and alcohol and is used in the fitness industry to improve the appearance of muscles.
When used sparingly it can make muscles look fuller and more aesthetic, but when abused it can make users look cartoonish.
Synthol is also known as Site Enhancement Oil (SEO), other substances such as sesame oil can also be used.
Synthol became popular in the 90s with bodybuilders, but before Synthol there were other alternatives. In fact a lot of bodybuilders used to inject steroids directly into muscles as this causes the muscles to swell temporarily.
To understand why bodybuilders would go to extreme lengths to “cheat” you must first understand the culture.
In bodybuilding aesthetics is pretty much all that matters, strength is not irrelevant but the competitions are never won by the strongest person.
The competition is won by the guy with the most symmetrical body. As such bodybuilders will try to build up every muscle so that they are evenly distributed.
Having huge biceps but tiny forearms will make their arms look less symmetrical which will cost them a good score. Having tiny legs and an overly large chest will also do this.
Obviously their goal is to make sure that no muscle is ignored, but sadly not all muscles grow at the same rate.
Calf muscles can be particularly difficult for many bodybuilders because of their fibre make up. When it comes to calf hypertrophy you were either born to have them or not.
So in an effort to win, bodybuilders would inject an oil or a steroid into their calf muscles (biceps, delts, and pectorals may also get the treatment) to “bring them up”. Problem solved!
Once Synthol became popular with bodybuilders it began to be used more and more. You’d struggle to find a bodybuilder these days who doesn’t use it to some extent, but as with everything in bodybuilding only the successful Synthol users get famous.
A professional bodybuilder will know where the line is between perfection and ridicule and will go right up to that line. An amateur may not be quite as aware of this line, and may end up overusing Synthol.
Signs of Abuse
Let’s be clear here, whether you’re a professional bodybuilder using Synthol to fashion beautiful delts or a bloke who is randomly jabbing needles into your arm 5 times a day you are abusing Synthol.
At the end of the day injecting your muscles with oil is insane. But we are here to look at the signs of overusing site enhancement oils, so let’s focus on the amateurs.
The most obvious side effect of chronic Synthol injections is muscles that have completely lost their ability to maintain a muscle shape. This is because they are so full of oil that they cannot create any definition.
You can begin to notice this slightly in professional bodybuilders, muscles such as the biceps brachii can maybe look a little bloated particularly around the origin and insertion of the muscle.
But in many amateurs the muscles have become so saturated that they look more like water balloons than muscles. In this case even someone who had never heard of Synthol would know that something was up!
Other than looking ridiculous, Synthol abuse has many other (much nastier) side effects. A case study in 2005 talks of a 21 year old bodybuilder who had been injecting himself with sesame oil. His body had reacted badly to it and caused vasculitis (where the body attacks healthy blood vessels leading to swelling and a weakening of the immune system) .
Another major issue is that the Synthol can prevent the muscles from receiving oxygen and nutrients, leading to the muscle catabolism (or exactly the opposite of what they want).
Infections are also a common problem, as is nerve damage, strokes, and many other issues.
The Bottom Line
It should be apparent to all that Synthol is a bad idea, but sadly bodybuilding is unique in its way to make people do desperate things for success.
No other sport rewards cheating so obviously, and that isn’t about to change any time soon. Entire competitions hinge on tiny percentages, little advantages that one competitor might have over another, with an all or nothing mentality leading to people taking extreme risks.
Outside of bodybuilding there are an increasing number of men from South American and Middle Eastern backgrounds who are turning to Synthol abuse.
Whilst in Europe and America these people are treated with derision, in their home countries the response is more positive. Even in Western countries you can still get famous by doing it, even if the attention is negative. Celebrity culture is always a great incentive for people to do stupid things to their bodies.
Try to stay away from Synthol at all costs, it is absolutely not worth the risk. But if you are going to do it, then go in smart. Don’t continually inject yourself until your arms are 28 inches round, it won’t end well for you.
 Koopman, M., Richter, C., Parren, R., Janssen, M. 2005. Bodybuilding, sesame oil and vasculitis. Rheumatology 44(9): 1135