Written and maintained by CASRAI Editorial Board
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General product and regulatory information only; it is not medical advice. For an allergy or a clinical decision, follow your clinician and the product’s own labeling.
Short answer
Polyisoprene is a rubber polymer built from isoprene units. Natural rubber latex is almost entirely cis-1,4-polyisoprene, and synthetic polyisoprene (often written IR) is manufactured to imitate it. In medical supplies it appears chiefly in surgical gloves and synthetic condoms, which FDA regulates under different device classes. The material is not the same as natural latex, and not the same as nitrile or PVC.
Definition and scope
A 2023 review in Polymers describes synthetic polyisoprene rubber as a mimic of natural rubber (NR). It reports that synthetic polyisoprene is typically 95 to 98% cis-1,4-polyisoprene, compared with almost 100% for natural rubber, and that material above 99% cis-1,4 has been made. The review notes that, unexpectedly, very high-cis synthetic rubber showed inferior mechanical properties compared with natural rubber.
The same review explains why the synthetic version exists for medical use. Natural rubber carries proteins and protein derivatives that can cause irritation and allergies, which raised demand for alternatives. It lists medical gloves, condoms and parts of medical and dental equipment among the applications of synthetic polyisoprene.
Polyisoprene properties
- Composition: 95 to 98% cis-1,4 for typical synthetic grades; almost 100% for natural rubber.
- Mechanical behavior: even synthetic grades above 99% cis-1,4 performed worse mechanically than natural rubber in the work the review summarizes.
- Protein content: the allergy concern attributed to natural rubber comes from its proteins and protein derivatives; the review presents synthetic polyisoprene as a substitute for natural rubber in medical gloves and condoms.
Synthetic rubber vs natural rubber
Synthetic rubber is rubber made from raw materials derived from petroleum, whereas natural rubber (NR) comes from latex, with Hevea brasiliensis as the main industrial source (99%) (Cruz-Morales et al., 2023). Polyisoprene is the synthetic rubber designed to imitate natural rubber, which is why it is the one most often compared with it in medical supplies. Other synthetic rubbers, such as nitrile and chloroprene, are different polymers and are not mimics of natural rubber.
| Point of comparison | Natural rubber | Synthetic polyisoprene (IR) |
|---|---|---|
| Origin | Latex, mainly from Hevea brasiliensis | Petroleum-derived raw materials, made after 1950 with Ziegler-Natta stereospecific catalysts |
| cis-1,4-polyisoprene content | Almost 100% | Typically 95 to 98% |
| Non-rubber components | A naturally occurring nanocomposite with proteins and lipids; latex contains 1.0 to 1.8% protein | Reported by the review as a substitute that avoids the natural rubber proteins |
| Strength | Higher tensile strength and tear resistance | Usually somewhat lower tensile strength and tear resistance; IR nanocomposites can fully mimic the mechanical properties of natural rubber |
| Use | Used in the same applications as IR | Often used in the same applications as natural rubber, including medical membranes |
FDA states that some people are allergic to the natural rubber latex used in some medical gloves, and that manufacturers must state the glove materials on the package. Which synthetic material a given product uses is therefore read from its labeling; see our guide to gloves and latex allergy.
Where it is used in medical supplies
The clearest regulatory trail is in FDA’s 510(k) premarket notification database. As of an openFDA query on 2026-10-30, 60 records carry “polyisoprene” in the device name. They include surgical gloves and a synthetic condom. Glove products are covered in more detail in our guides on latex gloves, nitrile gloves and chloroprene gloves.
How FDA records classify polyisoprene products
The same polymer reaches the market through different regulatory paths, depending on the device it is made into. The table below uses openFDA 510(k) and classification records checked on 2026-10-30.
| Example 510(k) record | Product code and name | Device class | Regulation | Decision date |
|---|---|---|---|---|
| K221748, Medispo Polyisoprene Surgical Gloves | KGO, Surgeon’s Gloves | Class 1 | 21 CFR 878.4460 | 2022-09-13 |
| K111868, sterile polyisoprene powder-free surgical gloves | KGO, Surgeon’s Gloves | Class 1 | 21 CFR 878.4460 | 2011-09-21 |
| K072169, Durex synthetic polyisoprene male condom | MOL, Condom, Synthetic | Class 2 | 21 CFR 884.5300 | 2008-06-19 |
21 CFR 878.4460 describes a non-powdered surgeon’s glove as a device worn by operating room personnel to protect a surgical wound from contamination, and classifies it as Class I (general controls). The regulation text does not mention polyisoprene; the material appears in the product names of the cleared devices, not in the regulation.
Natural rubber latex vs synthetic polyisoprene vs other alternatives
How the two rubbers compare on composition, the allergy concern and labeling:
| Question | Finding |
|---|---|
| Composition | Natural rubber is almost 100% cis-1,4-polyisoprene; typical synthetic polyisoprene is 95 to 98% (Cruz-Morales et al., 2023). |
| Allergy driver | Proteins and protein derivatives in natural rubber (Cruz-Morales et al., 2023). |
| What FDA names as synthetic glove alternatives for people allergic to natural rubber latex | PVC, nitrile and polyurethane. Polyisoprene is not named in that FDA list. |
| Where the material is stated | Manufacturers must identify the glove materials on the package labeling (FDA). |
Polyisoprene vs latex: what “latex” covers
“Latex” is a form, not a single material: a colloidal suspension of rubber particles in water. 21 CFR 801.437 defines “natural rubber latex” as rubber produced by a process that uses natural latex in a concentrated colloidal suspension, with products formed by dipping, extruding or coating. The Polymers review describes natural latex from Hevea brasiliensis as about 30 to 35% rubber, 1.0 to 1.8% protein and 50 to 70% water. So “polyisoprene vs latex” compares a synthetic polymer with a natural material that contains the same polymer plus proteins. Natural rubber latex is almost 100% cis-1,4-polyisoprene in its rubber fraction; synthetic polyisoprene is typically 95 to 98% (Cruz-Morales et al., 2023).
| Question | Natural rubber latex | Synthetic polyisoprene |
|---|---|---|
| Source | Natural latex, mainly from Hevea brasiliensis | Petroleum-derived raw materials |
| Natural latex proteins | Present (1.0 to 1.8% of the latex) | The review presents it as a substitute that avoids the natural rubber proteins |
| FDA natural-rubber labeling rule (21 CFR 801.437) | Applies to devices that contain it and contact humans | The rule’s definition of “natural rubber” does not list pure synthetic polyisoprene; it does cover synthetic latex or synthetic rubber that contains natural rubber in its formulation |
What is synthetic latex?
The term has no single definition across the sources checked. In the FDA labeling regulation it appears only inside the definition of “natural rubber,” which includes “synthetic latex or synthetic rubber that contains natural rubber in its formulation” (21 CFR 801.437(b)). That wording means a product sold as “synthetic latex” is not automatically free of natural rubber: whether it is covered by the natural-rubber labeling rule depends on its formulation, and the formulation is stated on the labeling, not by the name. Polyisoprene is one synthetic rubber designed to imitate natural rubber; FDA’s medical glove page names PVC, nitrile and polyurethane as other synthetic materials for people allergic to natural rubber latex. A name such as “synthetic latex” or “latex-free” does not by itself identify which of these polymers a product uses; the package labeling, which FDA requires to identify glove materials, does. See also our guides to gloves and latex allergy and latex-free dental dam labeling.
Where it matters for labs, clinics and supply decisions
FDA states that some people are allergic to the natural rubber latex used in some medical gloves, and that FDA reviews gloves for leak resistance, certain physical properties and biocompatibility. Because FDA requires material identification on the labeling, the label is the document that tells a clinic or lab which polymer a given glove or condom is made from. A product name that says “synthetic” or “latex-free” does not by itself say whether the material is polyisoprene, nitrile, PVC or polyurethane. For glove fit, see our guide to surgical glove sizes.
Common misunderstandings
“Synthetic polyisoprene is the same as natural rubber.”
It is designed to imitate it, but the review reports different cis-1,4 content (95 to 98% vs almost 100%) and, even at above 99%, inferior mechanical properties in the work it summarizes.
“All latex-free gloves are polyisoprene.”
No. FDA’s list of synthetic glove materials as alternatives to natural rubber latex names PVC, nitrile and polyurethane, so the material has to be read from the labeling.
“If it is regulated, it is regulated like a condom.”
No. In the records above, a polyisoprene surgical glove sits in Class 1 under 21 CFR 878.4460, while a synthetic condom sits in Class 2 under 21 CFR 884.5300. The class follows the device, not the polymer.
FAQ
What is polyisoprene?
A rubber polymer made of isoprene units. Natural rubber is almost 100% cis-1,4-polyisoprene; synthetic polyisoprene is typically 95 to 98% cis-1,4 (Cruz-Morales et al., 2023).
What are the properties of polyisoprene?
Its cis-1,4 content (typically 95 to 98%), a mechanical performance that stayed below natural rubber even at above 99% cis-1,4, and the absence of the natural rubber proteins that the review links to irritation and allergy.
Is polyisoprene used in medical products?
Yes. FDA 510(k) records include polyisoprene surgical gloves and a synthetic polyisoprene condom; the review also lists medical and dental equipment parts.
What is synthetic rubber?
Rubber made from raw materials derived from petroleum. Synthetic polyisoprene is the type designed to imitate natural rubber (Cruz-Morales et al., 2023).
What is the difference between synthetic rubber and natural rubber?
Natural rubber comes from latex and is almost 100% cis-1,4-polyisoprene, with proteins and lipids; synthetic polyisoprene is typically 95 to 98% cis-1,4 and usually has somewhat lower tensile strength and tear resistance (Cruz-Morales et al., 2023).
What is the difference between polyisoprene and latex?
Latex is a water-based colloidal suspension; natural rubber latex contains cis-1,4-polyisoprene plus about 1.0 to 1.8% protein. Synthetic polyisoprene is made from petroleum-derived raw materials, is typically 95 to 98% cis-1,4, and is presented as a substitute that avoids the natural rubber proteins (Cruz-Morales et al., 2023).
Is synthetic latex the same as natural latex?
No. FDA’s labeling rule treats “synthetic latex or synthetic rubber that contains natural rubber in its formulation” as natural rubber, so the formulation, stated on the labeling, decides how a product is covered (21 CFR 801.437(b)).
Is polyisoprene latex-free?
Synthetic polyisoprene does not come from natural latex, but a product name alone does not confirm its material; FDA requires manufacturers to identify glove materials on the package labeling.
Where do I find which material a glove is made of?
On the package labeling, which FDA requires to identify the glove materials.
Sources
All sources checked 2026-10-31.
- Cruz-Morales et al., “Synthetic Polyisoprene Rubber as a Mimic of Natural Rubber: Recent Advances on Synthesis, Nanocomposites, and Applications,” Polymers (Basel), 2023. https://pmc.ncbi.nlm.nih.gov/articles/PMC10610710
- U.S. FDA, Medical Gloves. https://www.fda.gov/medical-devices/personal-protective-equipment-infection-control/medical-gloves
- 21 CFR 801.437, User labeling for devices that contain natural rubber. https://www.law.cornell.edu/cfr/text/21/801.437
- 21 CFR 878.4460, Non-powdered surgeon’s glove. https://www.law.cornell.edu/cfr/text/21/878.4460
- FDA openFDA device 510(k) and classification endpoints. https://open.fda.gov/apis/device/510k/ and https://open.fda.gov/apis/device/classification/
