IngredientsCarbomers, also known as carboxypolymethylene, are a series of synthetic, high molecular weight and cross-linked poly-acrylic acid polymers, widely used in cosmetics and pharmaceutical industries for the formulation of semisolid and oral liquid products of various consistencies. The substance is identified under several interchangeable names in the scientific and regulatory literature. Carbomer is also known as carbopol or carboxypolymethylene and is a slightly acidic white powder comprised of cross-linked hydrocarbon chains. Additional synonyms recorded in official documents include carpolene, carboxyvinyl polymer, and polyacrylic acid.
Carbomer (CAS No. 9003-01-4; alternative names include carbomer 934 [9007-16-3]; carbomer homopolymer Type C [9007-17-4]; carbomer 941 [9062-04-08]; and carbomer carboxypolymethylene [9007-20-9]) is also commercially known as Acrypol, Acritamer, Carbopol, Pemulen, and Tego Carbomer.
Carboxypolymethylene is an entirely synthetic polymer; it has no botanical or natural biological source. Carbomer is formed from the monomer acrylic acid, which is polymerised and crosslinked with allyl pentaerythritol (APE). The polymers are synthesised in ethyl acetate using a free-radical polymerisation initiator.
Carbomers differ by the cross-linker and its density, and the solvent used during their polymerisation. Based on the cross-linker type, carbomers can be grouped into carbomer homopolymers (acrylic acid crosslinked with allyl sucrose or allyl pentaerythritol), carbomer copolymers (acrylic acid and C10–C30 alkyl acrylate crosslinked with allyl pentaerythritol), and carbomer interpolymers (carbomer homopolymer or copolymer that contains a block copolymer of polyethylene glycol and a long-chain alkyl acid ester).
Initially, Carbopol® polymers were polymerised in benzene. Over time, Lubrizol expanded its product offering to include products polymerised in toxicologically preferred solvents such as ethyl acetate or a cosolvent mixture of ethyl acetate and cyclohexane.
Carbomer is a white fluffy powder with a characteristic slight odor. Based on dry weight, carbomers have carboxylic acid groups that range from 56% to 68% w/w. Because the molecular structure contains 52%–68% acidic groups, it has a certain acidity; the pH value of a 1% aqueous solution is 2.5–3.0.
When dispersed in water, carbomer molecules swell partially and form a solution of low viscosity; when neutralised with water-soluble alkali, the resin molecules swell completely and form a high-viscosity gel. When carbomers are hydrated in water they form acidic solutions that become increasingly viscous and gel-like if the pH is adjusted to a more alkaline environment (typically above 4–6). During the neutralisation process, the polymer chains become ionised and internal repulsion between polymer strands forces the polymer to uncoil and to enhance viscosity. The gel achieves maximum viscosity at pH 6 to 12; when pH falls below 3 or rises above 12, the viscosity decreases.
The resulting molecular weight range of the polymer is from about 2×106 daltons to about 1×109 daltons, with an average molecular weight of about 4×106 daltons.
Carbomer has been included in the United States Pharmacopeia, British Pharmacopoeia, Chinese Pharmacopoeia, and others. It is a multi-purpose polymer material and pharmaceutical auxiliary material. Due to its good adhesion, gelation, emulsification, thickening, suspending, and film-forming properties, it is widely used in the pharmaceutical industry, daily chemical industry, and other related industrial fields.
In January 2006, the U.S. Pharmacopeia/National Formulary (USP 29-NF 24) introduced a new umbrella monograph called "Carbomer Homopolymer," which applies to homopolymers manufactured without the use of benzene as a polymerisation solvent. The Carbomer Homopolymer monograph includes three different types based on viscosity (Type A, Type B, and Type C).
There are different types of Carbopol, designated by a number. The most commonly used in pharmacy are Carbopol 934 and Carbopol 940. Those that carry the letter "P" after the number are of high purity, with a controlled residual benzene content, which makes them suitable for oral use (e.g., as a binder in tablets).
Two grades of carbomer can be manufactured by varying the amount of the crosslinker APE used in the polymerisation reaction: Carbopol® 974P NF Polymer, defined as "highly crosslinked," and Carbopol® 971P NF Polymer, defined as "lightly crosslinked," thus resulting in polymers with different viscosities. A third grade, Carbopol® 71G NF Polymer, can be obtained from Carbopol® 971P NF Polymer via dry granulation to give a different particle size.
Carbomers, defined as high molecular mass polymers of acrylic acid cross-linked with polyalkenyl ethers of sugars or polyalcohols with 56–68% of carboxylic acid groups (for the dried substance), are used in pharmaceutical products and recognised as excipients in the European Pharmacopoeia (European Pharmacopoeia 10.5, 2021).
The readily water-swellable Carbopol polymers are used in a diverse range of pharmaceutical applications to provide controlled release in tablets; bioadhesion in buccal, ophthalmic, intestinal, nasal, vaginal, and rectal applications; and thickening at very low concentrations to produce a wide range of viscosities and flow properties in topical lotions, creams, gels, oral suspensions, and transdermal gel reservoirs.
These polymers are effective thickeners, suspending agents, and stabilisers at very low concentration (0.1–3% w/w). Carbopol is used as an emulsifying, viscosifying, suspending, and gelling agent in formulas such as solutions, suspensions, creams, gels, and ointments, which can be administered ophthalmically, rectally, and topically.
Carboxypolymethylene, also known as carbomer, is a synthetic high-molecular-weight polymer of acrylic acid. Historically, its primary medicinal use has been as an excipient rather than a direct remedy, but its contributions have been significant in the advancement of modern pharmaceutical and nutritional formulations. Introduced in the mid-20th century, carboxypolymethylene's unique ability to form clear, stable gels and efficiently thicken aqueous solutions revolutionised the texture, stability, and delivery of many oral and topical medications.
Because carboxypolymethylene is an entirely synthetic compound first developed in the industrial era, it has no traditional or ethnobotanical history of use. It does not appear in pre-modern herbal medicine, traditional Chinese medicine, Ayurveda, or any other historical medical tradition. Any claims linking it to ancient or traditional practices are unsupported by the authoritative literature.
Several properties of Carbopol make it potentially valuable as a pharmaceutical excipient in numerous applications. Carbopol has been used in controlled-release solid dosage formulations for the last four decades, and the number of manufacturers commercialising controlled-release tablets using carbomers has increased considerably in recent periods.
In medicinal applications, carboxypolymethylene has enabled the creation of palatable, easy-to-swallow gels and suspensions for those who have difficulty with traditional pills. Its inert, non-toxic, and biocompatible nature makes it an ideal vehicle for delivering both pharmaceutical drugs and nutritional supplements, ensuring even distribution and consistent dosing of active ingredients.
Carboxypolymethylene is not a mixture of active phytochemicals — it is a single, well-defined synthetic polymer. Carbopols/carbomers are high molecular weight acrylic acid polymers linked to allyl sucrose. Based on dry weight, these have carboxylic acid groups ranging from 56% to 68% w/w. These densely spaced carboxylic acid (–COOH) groups are responsible for the polymer's key functional and biological interactions.
When dispersed in water, carbomer molecules swell partially and form a low-viscosity dispersion; when neutralised with water-soluble alkali, the resin molecules swell completely and form high viscosity. The gelation speed and water-swelling degree of carbomer are related to electrostatic force. When the degree of carbomer dissociation is high, it is easier to form a gel.
When neutralised with alkali, as the macromolecules gradually dissolve, the viscosity gradually rises, forming a clear solution at low concentrations and a translucent gel at higher concentrations. The gel pH has maximum viscosity from 6 to 12.
Carbomers are extensively used in controlled drug delivery systems (CDDS). They are also finding numerous applications in oral mucoadhesive drug delivery because of their ability to interact with the mucus glycoprotein and to remain localised to a specific site.
Carbomers contain 56%–68% of carboxylic acid groups calculated on the dry basis. These are used as suspending agents or viscosity-increasing agents, dry and wet binders, as well as rate-controlling agents in tablets, and enzyme inhibitors of intestinal protease in peptide-containing dosage forms.
Carbomer 934 exhibits the strongest bioadhesion through carboxyl group interactions with mucosal surfaces. This extends drug residence time in nasal, vaginal, rectal, and oral cavities while reducing ciliary clearance.
BufferGel™ or Carbopol 974 is a carbopol polymer formulated with a buffering agent that has the ability to buffer twice its volume in semen to pH ≤ 5. It is a microbicide candidate designed to maintain the acidic pH of the vaginal tract. This acidifying property underlies its investigation as a mucosal protective and antimicrobial agent.
Carbomer showed no evidence for systemic availability or biotransformation in an in vivo study in rats dosed by gavage with three 14C-labelled poly(acrylic acid) polymers of different average molecular weights and degrees of cross-linking. Studies have demonstrated that carboxypolymethylene is not absorbed systemically and is excreted unchanged, minimising the risk of toxicity.
Important framing note: Carboxypolymethylene/carbomer is classified by major regulatory bodies as a pharmaceutical excipient — an inert carrier or formulation agent — rather than as a pharmacologically active substance. There is limited evidence to suggest any direct nutritional benefit from carboxypolymethylene itself; its contributions to the safety, stability, and acceptability of nutritional products are well established. The clinical investigations described below typically evaluate carbomer as a functional vehicle or as a formulation component, not as a pharmacologically active principle in the traditional supplement sense.
Carbopol® 980 NF is the most efficient thickener of all Carbopol® polymers on the market. Furthermore, it is already incorporated in commercial ophthalmic gels to treat dry eye syndrome. GelTears is a sterile, viscous ophthalmic gel specifically formulated to function as a substitute for natural tears. In the management of ocular surface diseases, particularly keratoconjunctivitis sicca (dry eye syndrome), the maintenance of a stable tear film is paramount for corneal health and visual clarity. Unlike conventional aqueous eye drops that often require frequent instillation due to rapid drainage, GelTears utilises a semi-solid formulation based on Carbomer 980 to provide prolonged retention time on the ocular surface.
Clinical evidence: The efficacy and safety of a carbomer-containing ocular gel was compared to a commonly used 1.4% polyvinyl alcohol (PVA) artificial tear preparation in a multicentre, randomised, open cross-over study in 61 patients with symptoms and signs of dry eyes, who were treated with each preparation separately for two weeks. Additional randomised controlled studies comparing carbomer gel to polyvinyl alcohol in dry eye patients are indexed in the Cochrane CENTRAL database, including studies by Brodwall et al. (1997) and Bron et al. (1998). A placebo-controlled study evaluated the efficacy and safety of 0.3% carbomer gel in patients with moderate-to-severe dry eye syndrome (Sullivan et al., Ophthalmology, 1997;104:1402–1408).
The main component of commercial ophthalmic carbomer products is Carbopol 980 NF, a water-soluble polyacrylic acid with good mucoadhesion. It gives the gel the chemical-physical properties of viscosity and elasticity necessary for proper lubrication of the eyelids, forming a stable fluid film on the outer eye to provide protection to the eye surface, particularly at night.
Evidence strength: Multiple small-to-moderate randomised trials in human patients support the use of carbomer 0.2%–0.3% ophthalmic gels as tear substitutes in dry eye syndrome. Evidence is moderate strength for symptomatic relief in dry eye, but head-to-head comparisons with other artificial tear formulations yield mixed results on superiority. The evidence base supports non-inferiority rather than superiority to other artificial tear preparations.
BufferGel (Carbopol 974P): Carbomer has been extensively investigated as the active structural component of BufferGel, a vaginal microbicide candidate. BufferGel (ReProtect, LLC) is a vaginal gel with an acidic buffering action designed to prevent vaginal neutralisation by semen. A study evaluated the safety and tolerability of BufferGel applied vaginally either once or twice daily by 27 women who were at low risk for acquisition of HIV. Participants initially used the product once daily for 14 days and then twice daily for 14 days; they underwent colposcopy before and after product exposure.
BufferGel was well tolerated, although two-thirds of the participants reported at least one mild or moderate adverse experience. The most common adverse events were irritative genitourinary symptoms. Product use was discontinued after 3 adverse events. BufferGel was well tolerated in women at low risk for acquisition of HIV; toxicity was limited and occurred at frequencies similar to those in women who did not use any vaginal product and at levels lower than in women who used detergent-based microbicides.
A larger Phase I international safety study enrolled 98 women at four sites. HIV/STD-negative, sexually abstinent, and sexually active women in India, Thailand, Malawi, and Zimbabwe were asked to insert one applicator (approximately 5 mL) of BufferGel vaginally twice per day for 14 days. Sexually active women agreed to have sex (while using BufferGel and nonlubricated condoms) at least twice per week. In total, 98 women (30 sexually abstinent and 68 sexually active) were enrolled. Overall compliance with product use was 93%. Epithelial abnormalities detected by pelvic examination or colposcopy were uncommon (8 cases in 271 examinations). Irritation was reported by approximately one quarter of the women (0.58 events per woman-week) but was generally mild and of short duration.
The prevalence of bacterial vaginosis (BV) fell significantly, from 30% at enrolment to 6% at one week, and 7% at two weeks of BufferGel use. Thirty-two women acquired microscopically detectable yeast during BufferGel exposure, but only 3 developed symptomatic vaginitis. BufferGel appears to be safe and well tolerated by the cervicovaginal epithelium. Its effect on BV and yeasts merits further study.
However, BufferGel was unable to prevent HIV-1 transmission during a clinical trial conducted in Southern Africa and the USA (Abdool Karim et al., 2011).
Evidence strength: Phase I and early Phase II evidence demonstrates good local tolerability and preliminary activity against bacterial vaginosis. However, efficacy for the prevention of HIV transmission was not demonstrated in a large Phase II/III trial. Evidence for vaginal carbomer gel in BV management is preliminary; carbomer in this context functions primarily as a buffering vehicle and cannot be considered an established therapeutic agent.
Two randomised clinical trials evaluated 0.5% carbomer 980 gel as an intranasal spray for the common cold. Study 1 randomly assigned healthy adults to 0.5% carbomer 980 gel (n = 20) or placebo (n = 10) administered intranasally four times daily for 7 days; nasal examinations were conducted at baseline and daily throughout the study, with the primary endpoint being local nasal tolerability. Study 2 randomly assigned adults with an investigator-confirmed diagnosis of symptomatic common cold to 0.5% carbomer 980 gel (n = 87) or placebo (n = 81), administered intranasally four times daily for 7 days. The primary efficacy endpoint was the average nasal symptom score over days 1–4. Secondary efficacy endpoints included average nasal symptom score over days 1–7 and average total symptom score.
While 0.5% carbomer 980 gel nasal spray demonstrated good local nasal tolerability in healthy volunteers, the spray did not significantly impact the course of infection or resolution of cold symptoms in subjects with common cold.
The dosing employed was 3 actuations per nostril per dose; each actuation was 140 µL, equivalent to 140 mg, administered 4 times per day.
Evidence strength: Based on two randomised controlled trials (one tolerability, one efficacy), intranasal carbomer 980 gel at 0.5% concentration demonstrated acceptable local tolerability but did not significantly reduce nasal cold symptoms. Evidence for this indication is weak and negative for efficacy.
Several properties of Carbopol make it potentially valuable as a pharmaceutical excipient in numerous applications; it has been used in controlled-release solid dosage formulations since the last four decades. Tablet formulations using Carbopol polymers have demonstrated zero-order and near zero-order release kinetics. In this way carbomers act as efficient controlled-release agents for matrix tablets and also improve bioavailability of certain drugs.
Carbomer-based systems have been used commercially in FDA-approved systems, mainly as an inactive excipient that promotes mucoadhesion and long-lasting drug release.
The use of carbomers in oral delivery of peptides or protein-based drugs is also covered in the literature. Carbomers are used as suspending agents or viscosity-increasing agents, dry and wet binders, as well as rate-controlling agents in tablets, and as enzyme inhibitors of intestinal protease in peptide-containing dosage forms.
Evidence strength: The application of carbomer in oral controlled-release tablets is well-established at the formulation science level, backed by decades of pharmaceutical use in commercial products. However, the evidence here pertains to carbomer as an excipient for delivering other active substances, not as a pharmacologically active supplement ingredient in its own right.
Carbomer or known as Carbopol is a mucoadhesive polymer that is widely studied for topical delivery of pharmaceutical agents to the mucous membrane. The use of Carbopol and its advantages in the mucoadhesive topical application have gained considerable interest with several published studies; it is available in various grades.
Disadvantages of mucosal drug delivery that carbomer addresses include low residence time of the medication on the site of application due to tongue movement and salivary washout in the intraoral formulation, mucociliary clearance in intranasal application, and rapid precorneal elimination in intraocular formulations.
After thickening, carbomer can adhere to the oral mucosal surface for a long time, forming a thin film that prolongs drug release and action time, and plays a physical isolation role. This property has been investigated for local anaesthetic delivery, aphthous ulcer management, and antifungal therapy in the buccal cavity.
Evidence strength: Research in mucoadhesive buccal delivery systems using carbomer is predominantly preclinical and formulation-stage. While carbomer has been incorporated into commercial approved buccal drug delivery products, the human clinical evidence for any standalone therapeutic effect of carbomer itself in this setting is limited.
The application of carbomer as a food additive — rather than a pharmaceutical excipient — has been specifically reviewed by the European Food Safety Authority (EFSA). The EFSA Panel on Food Additives and Flavourings (FAF) provides a scientific opinion on the safety of crosslinked polyacrylic acid polymers (carbomer) proposed for use as a food additive in solid and liquid food supplements.
The EFSA Panel concluded that the available data were adequate to evaluate safety. Carbomer was negative in the basic test battery of in vitro genotoxicity assays, consisting of a bacterial reverse mutation assay (OECD TG 471) and an in vitro mammalian cell micronucleus test (OECD TG 487). The Panel therefore considered that carbomer does not raise a concern with respect to genotoxicity.
Considering the available data set, the Panel derived an acceptable daily intake (ADI) of 190 mg/kg body weight per day.
Evidence strength: The body of evidence supports the safety of carbomer as a food supplement excipient at regulated doses, but there is no evidence that carbomer itself confers any nutritional or health benefit in food supplement applications. It is evaluated solely as a structuring and stabilising agent.
The following dosages are reported directly from primary sources and regulatory documents. Because carbomer is an excipient, concentrations are typically expressed as a percentage of the total formulation rather than as a supplement serving size.
In vivo data showed no evidence for systemic availability or biotransformation of carbomer. Carbomer does not raise a concern regarding genotoxicity. Because of the lack of systemic availability, the EFSA Panel considered that the biological and toxicological data were adequate to conclude on the safety of the proposed new food additive.
A critical safety signal identified in animal toxicology studies is potential nutrient malabsorption at high doses. From the sub-chronic 13-week study in rats, effects on body weight and body weight gain were observed as well as some minor effects in clinical chemistry parameters. The Panel considered that these decreases could be reflective of interactions between nutrients and carbomer resulting in nutrient malabsorption, which is considered an undesirable effect. The Panel confirmed that despite no clear signs of toxicity at any dose level tested, the decreases in body weight and body weight gain along with changes in clinical chemistry in the high-dose groups would be reflective of nutrient malabsorption following interactions of nutrients in the GI tract with carbomer.
Specifically, in high-dose females, there were decreases in calcium, potassium, and chloride concentrations as well as a slight increase in aspartate aminotransferase activity (but not in alanine aminotransferase). No toxicologically relevant gross pathology or histopathology findings were reported.
Carbomer was negative in the basic test battery of in vitro genotoxicity assays — a bacterial reverse mutation assay (OECD TG 471) and an in vitro mammalian cell micronucleus test (OECD TG 487) — and the Panel therefore considered that carbomer does not raise a concern with respect to genotoxicity.
GelTears (carbomer 980) creates a viscous barrier on the corneal surface. If other eye drops (e.g., for glaucoma, antibiotics, or steroids) are instilled after carbomer gel, their penetration into the eye will be significantly reduced or blocked. The recommended interval is at least 15 minutes between instilling any other eye drops and carbomer gel. Carbomer gel should always be administered last; aqueous drops should be used first, then the gel.
Blurred vision may occur after use; patients should not drive or use machines until vision is clear. Soft contact lenses should not be worn with most carbomer gels due to preservatives. The gel should not be used if the container has been open for more than four weeks.
BufferGel (carbopol 974) was well tolerated, although two-thirds of the participants reported at least one mild or moderate adverse experience. The most common adverse events were irritative genitourinary symptoms. Product use was discontinued after 3 adverse events.
Carbomers are compatible with most of the ingredients used in personal care and pharmaceutical formulations. Soluble salts, such as sodium chloride, decrease the efficiency of carbomer resin mucilage. Salt electrolytes reduce carbomer gel viscosity through charge-screening effects on the polymer network. Alkaline earth metal ions can form insoluble salts with carboxyl groups, while strong acids cause permanent viscosity loss. These interactions are relevant to formulators rather than to end users, but they indicate that carbomer-based gels may behave differently when combined with physiological fluids high in ionic strength.
Initially, Carbopol polymers were polymerised in benzene. This posed a potential safety issue for pharmaceutical and oral applications. The U.S. Pharmacopeia decided to officially omit five types of carbomer — 940, 941, 1342, 934, and 934P — with benzene content greater than 2 ppm from the monograph on August 1, 2025. Carbomer grades designated with the letter "P" (for purity) have a controlled residual benzene content, which makes them suitable for oral use. Purchasers and formulators of carbomer for ingested supplement applications should verify that grades used meet current pharmacopoeial limits for residual solvents.
Regulatory bodies such as the U.S. Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA) have evaluated carbomer and classified it as Generally Recognised As Safe (GRAS) when used within specified limits. The safety of carbomers was assessed by the American College of Toxicology in 1982 and re-evaluated in 2002; the conclusion was that carbomers are safe for use in humans.
Carbomer is included in the European Commission database for information on cosmetic substances and ingredients (CosIng), where its functions are reported to be emulsion stabiliser, gel formation, and viscosity control.
Health conditions that Carboxypolymethylene may help support.
Body systems that Carboxypolymethylene may help support.
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