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Not medical advice. The Atlas is not a substitute for a clinician who can examine you.

Site-Enhancement Oils (Synthol / PMMA)

Oil and filler injected for cosmetic muscle size, the disfigurement and embolism danger

Evidence grade 4 of 5, Strong. Read how the Atlas grades evidence.

The written rationale for this grade is still being prepared.

FDA
Not applicable (unapproved cosmetic self-injection; no medical indication)

Reference only. Not medical advice.

What can go wrong

Documented complications span painful chronic muscle fibrosis and disfigurement, nerve damage, ulceration and infection, granuloma, hypercalcemia, and pulmonary granulomatosis; systemic and potentially fatal events include oil embolism, myocardial infarction, and stroke. Treatment frequently requires surgical removal of affected tissue, which is itself disfiguring. There is no legitimate medical use for these injections.

This is something to take to a clinician. The Atlas can tell you what is known about site-enhancement oils (synthol / pmma) in general. It cannot tell you what is happening in your body, and the difference matters most for exactly the symptoms that bring people to this page.

Site-enhancement oils ('site oils', Synthol) are injected directly into muscle to inflate its size cosmetically, not to build tissue. A typical formula is roughly 85% medium-chain triglyceride oil with lidocaine and alcohol. Case reports document painful chronic muscle fibrosis, a 'Swiss-cheese' cystic pattern on imaging, granuloma, ulceration, and disfigurement requiring surgical excision; systemic reports include oil (fat) embolism, pulmonary granulomatosis, hypercalcemia, myocardial infarction, and stroke. PMMA (polymethylmethacrylate) and other permanent fillers used similarly add non-resorbable foreign-body reactions. Intravascular injection can be fatal via pulmonary or cerebral embolism.

It doesn't build muscle. It fills the muscle with oil, and sometimes fills a vessel.

What people take it for

What it is taken for. Approval, where it exists, covers only some of these.

  • Cosmetic inflation of muscle appearance in bodybuilding
  • Marketed deceptively as a shortcut to muscle 'size'

How it works

The oil is deposited within or between muscle fibers, mechanically expanding the muscle's apparent volume. There is no anabolic effect and no functional strength gain. Over time the body walls off the oil with inflammation and fibrosis, producing the imaging appearance of scattered cystic fatty lesions and, histologically, chronic inflammation with fibrosis.

Why the embolism risk is the acute killer

The chronic disfigurement is the visible harm, but the acute danger is vascular. If oil or filler enters a vein or artery during injection, it can travel to the lungs (pulmonary embolism) or brain (cerebral embolism) with potentially fatal or stroke-causing results. Unlike a resorbable drug, injected oil and especially permanent fillers like PMMA cannot be readily removed once dispersed, and foreign-body reaction is lifelong.

Safety in detail

  • Chronic muscle fibrosis and permanent disfigurement
  • Oil/fat embolism -> pulmonary or cerebral, potentially fatal
  • Granuloma, ulceration, infection, nerve damage
  • PMMA/permanent filler: non-resorbable foreign-body reaction for life

What people get wrong

  • Often said'Synthol builds muscle'

    ActuallyIt inflates appearance with oil; it produces no muscle tissue and no strength.

  • Often said'It's just cosmetic and low-risk'

    ActuallyCase reports document embolism, MI, stroke, and disfigurement requiring surgery.

Who profits, and who pushes back

Nobody is named here yet, because we have not done that work on this entry. Read that as unfinished. Somebody almost certainly sells this, and somebody almost certainly disputes it. Assume both until we have checked.

What we do not know

  • What is the true rate of embolic events among site-oil users, given underreporting?
  • How often does attempted surgical correction fully resolve the disfigurement versus leaving permanent deficit?

At a glance

What it is
Oil (often ~85% MCT + lidocaine + alcohol) injected into muscle for size
It does NOT
Build muscle tissue, it displaces/inflates with oil
Local harms
Fibrosis, 'Swiss-cheese' cysts, granuloma, ulcer, disfigurement
Systemic harms
Oil embolism, pulmonary granulomatosis, MI, stroke

What this entry does not yet cover

What follows is unfinished work on our side, not a finding about Site-Enhancement Oils (Synthol / PMMA). A short entry is not a safe entry.

  • Timeline. We have not built the dated record of research and regulatory events.
  • Cost and market. We have not documented what it sells for or who sells it.
  • Supply chain. We have not mapped where it is made.
  • Who uses it. We have not documented the user groups.
  • What could change. No forward-looking summary yet.
  • How it compares. We have not set it against the alternatives.
  • Children and teenagers. We have not checked what is known about younger people.

Sources

The studies below are named and described, but not linked. You cannot open them from here and check our reading against them, which means this page is our summary of the literature rather than a document you can verify. Weigh it accordingly until the links exist.

The studies that matter

  • Painful muscle fibrosis after Synthol injection (case report)2012

    MRI 'Swiss-cheese' cystic pattern; histology showed inflammation and fibrosis; required surgical management

  • Synthol systemic complications (case report)2021

    Documented hypercalcemia and pulmonary granulomatosis attributed to injected site-enhancement oil