What Is Synthol? – Uses, Abuse And Injection Effects!

Synthol is an oil that some bodybuilders inject straight into a muscle to make it look bigger. It is not a steroid and it does not build muscle. The size it adds is oil, swelling and, over time, scar tissue. That is why heavy users end up with arms, shoulders or chests that look round, soft and out of proportion with the rest of the body.

Those physiques often get blamed on steroids. People who see the most extreme steroid before-and-after photos online tend to assume the drugs did it. But anabolic steroids build real muscle tissue across the whole body. Synthol only inflates the spot where it is injected.

This guide covers what synthol is, where it came from, why people use it, how use tends to escalate, and what the medical literature reports about its effects: infection, oil cysts, permanent muscle damage and oil embolism.

What Is Synthol?

Synthol is the best-known brand of site enhancement oil, or SEO. SEOs are oils injected into a muscle to make it look fuller. They are not hormones and have no anabolic effect: they do not make muscle fibers grow. The name “synthol” is now used loosely for any oil injected this way, including home-made blends.

The commonly cited formula for the original product is:

• 85% oil: mostly medium-chain triglycerides (MCTs), a type of fat usually made from coconut or palm kernel oil.
• 7.5% lidocaine: a local anesthetic that dulls the pain of injecting.
• 7.5% alcohol: acts as a preservative.

Home-made SEOs are often based on other oils, such as sesame oil, mixed with benzyl alcohol and benzyl benzoate, the same carriers used in many injectable steroids. They are made outside any regulated facility, so there is no guarantee they are sterile or contain what the maker says.

Synthol is injected directly into the muscle the user wants to enlarge. Once there, the oil does not simply sit in place like a filler. Part of it is broken down and cleared over time, but part stays in the tissue. The body reacts to it as a foreign substance, with inflammation and scar tissue that wall it off. That reaction is a large part of the size users see, and it is why the swelling can persist long after the injections stop.

Where Synthol Came From

Synthol is usually credited to a German named Chris Clark, who is said to have developed and sold it in the 1990s. He is sometimes described as a scientist, but there is no reliable record of his background. Accounts of the product’s origin come mostly from bodybuilding media and forums rather than any formal source, so treat the details as the commonly told story rather than established fact.

People had been injecting oils to change their body shape long before then. The pitch for synthol was that MCT oil was more stable and less likely to cause reactions than the cooking oils some bodybuilders had been using. Those claims came from marketing, not from clinical testing, and the complications covered below show the product is far from safe.

Sold as a “Posing Oil”

Synthol and similar products are sold online as “posing oils,” the oils bodybuilders rub on their skin to show definition under stage lights. That label is how they can be sold openly. They are not approved for injection by any medicine regulator, and the label makes them no safer to inject.

Few buyers want an SEO for their skin. Its real use, as an injection to enlarge muscles, is documented in the medical literature.

Synthol vs Anabolic Steroids

Synthol is often confused with steroids, and steroid users sometimes add SEOs to bring up a body part they think is lagging. The two work in completely different ways:

Steroids carry serious risks of their own, but they build real muscle. The classic physiques of the 1970s, including Arnold Schwarzenegger’s (he has openly said he used steroids), were muscle. Synthol only adds oil and scar tissue to a single spot.

Why Do Bodybuilders Use Synthol?

Bodybuilding is judged on size, conditioning and symmetry. A competitor with big arms, legs and back but flat shoulders or thin calves loses out on balance, and some muscle groups refuse to grow no matter how hard they are trained.

The idea behind SEOs is to fill that gap: a small amount of oil in a lagging muscle, like a sculptor adding a little clay to bring one part of a statue into proportion. Used that way, the change is meant to go unnoticed. Arms, shoulders and calves are the usual targets.

Rumors that some top professional bodybuilders have used small amounts of oil this way have circulated for decades. None of it is proven, and it would not make the practice safe. Infection and oil embolism can follow a single injection.

What synthol cannot do is build muscle. It adds no strength, and the size it adds is not muscle tissue.

How Synthol Use Gets Out of Hand

The physiques that made synthol infamous look nothing like a subtle fill. The injected muscles are hugely swollen, round and smooth, out of all proportion with the forearms, waist and legs. They look less like muscle than like something placed under the skin.

Those results usually come from not understanding what the oil does, combined with the pressure to look big fast. A typical pattern: a young lifter trains for months with little change in his arms. Someone offers him an oil that makes his biceps look bigger within days. He injects it and likes the result, then notices his biceps now look out of proportion with his triceps or shoulders, so he injects there too. Each round fixes one imbalance and creates another.

Body image plays a part. Muscle dysmorphia, a recognized form of body dysmorphic disorder, makes people see themselves as too small however big they get. For someone in that mindset, a product that adds size almost overnight is very hard to stop using.

Media reports from several countries have shown young men who injected large volumes of oil, or substances such as petroleum jelly, into their arms and later needed surgery to remove it.

To a trained eye, SEO use is easy to spot. The muscle shows no separation, its shape is round rather than anatomical, and only certain muscles are enlarged. Our guide to spotting a fake natty covers the signs of drug use more generally.

Gregg Valentino and “The Man Whose Arms Exploded”

The best-known name linked to synthol is Gregg Valentino, an American bodybuilder famous for the size of his arms. He was the subject of a documentary called The Man Whose Arms Exploded, which is widely known in bodybuilding circles.

Valentino has denied using synthol. He has said his size came from heavy steroid use, which he has talked about openly. Many in bodybuilding still suspect SEO use because of the shape of his arms. That is speculation: there is no public proof either way.

In the documentary, an injection site in his biceps becomes badly infected and he is shown draining it himself with a syringe. He has put his problems down to steroids and infection, not synthol. Whatever the cause, it is a clear picture of what an infected injection site in a large muscle looks like, and of why it needs a doctor rather than a needle at home.

Infection is a risk of any injection into a muscle, including steroid injections such as testosterone enanthate. With SEOs, oil left sitting in the tissue, and home-made oils that may not be sterile, add to that risk.

Synthol Side Effects and Injection Risks

No clinical trial has ever tested synthol, and none could ethically be run. What is known comes from case reports, case series and imaging studies of people who were treated for complications. That evidence is limited, but it points in one direction.

1. Escalating Use

Users often describe SEOs as habit-forming in a practical sense. Part of the oil is cleared over the following months and the swelling settles unevenly, so a muscle that was evened out looks small again. The usual response is to inject again, often more, to make it last. Over time the goal shifts from filling one gap to fixing every imperfection with oil.

2. An Unnatural-Looking Physique

Synthol is meant to make a body look better, and in heavy users it does the opposite. Injected areas swell while the rest of the body stays the same, so the arms or shoulders look inflated and detached from the frame around them. The skin over the swelling can become tight and lumpy.

3. Oil Cysts (Oleomas) and Scar Tissue

When the body cannot clear injected oil, it walls it off. Doctors call the resulting lumps oleomas, oil granulomas or sclerosing lipogranulomas: hard nodules and cysts of trapped oil surrounded by inflamed, scarred tissue. They are a well-documented reaction to injected oils of many kinds, not just synthol.

Oleomas can be painful, can become infected, and can break down the skin over them. They often do not go away on their own. Treatment may mean surgery to cut out the affected tissue, which leaves scars and does not always remove everything.

4. Permanent Muscle Damage

Repeated oil injections can destroy the muscle they were meant to improve. Published reports of bodybuilders who injected oil over long periods describe muscle tissue replaced by oil cysts, chronic inflammation and fibrous scar tissue. In the worst cases this progresses to necrosis of the muscle, meaning the tissue dies.

Scarred muscle does not work like healthy muscle. It can be stiff and weak, and the damage is often permanent even after the oil is removed.

5. Oil Embolism

Synthol is mostly oil, and oil does not mix with blood. If the needle enters a vein, oil can travel through the bloodstream to the lungs and block small blood vessels there. This is called pulmonary oil embolism, and case reports describe it in people who injected SEOs and other oils. Symptoms include sudden shortness of breath, chest pain and coughing.

Oil embolism can be life-threatening. Once oil is in the bloodstream there is nothing a user can do at home: it needs emergency medical care.

6. Infection and Abscesses

Every injection can carry bacteria from the skin, the needle or the oil into the muscle. A pool of oil in the tissue gives those bacteria somewhere to grow, and home-made oils may not be sterile to begin with. Reported complications include abscesses (pockets of pus), cellulitis (a spreading skin infection) and infected oleomas.

Abscesses usually need to be drained or surgically opened by a doctor, on top of antibiotics, and they can leave large scars. A deep infection that is left untreated can spread to the blood (sepsis), which can be fatal.

Warning Signs That Need a Doctor

Anyone who has injected synthol or any other oil should get medical help for:

• A hot, red swelling at an injection site that gets more painful or spreads
• Fever, chills or feeling generally unwell after injecting
• Sudden shortness of breath, chest pain or coughing, especially soon after an injection (call emergency services)
• Hard lumps that grow, hurt or break through the skin
• Numbness, tingling or weakness in the injected limb

Tell the doctor exactly what was injected. Knowing that the problem involves oil helps doctors choose the right scans and treatment.