Dimethyl Isosorbide
Also known as DMI, Dimethyl isosorbide, Isosorbide dimethyl ether, 1,4:3,6-Dianhydro-2,5-di-O-methyl-D-glucitol
“No regulator has issued a verdict on this ingredient.”
Dimethyl Isosorbide (DMI; CAS 5306-85-4; C8H14O4) is a glucose-derived cyclic ether solvent produced by methylation of isosorbide. It functions in cosmetics as a solvent and penetration enhancer, widely used in vitamin C and retinoid serums to improve solubilization and delivery of actives. Peer-reviewed literature confirms its skin penetration properties: in hairless mouse skin, DMI alone traversed skin at 12% over 24 hours, and 40% permeated in combination with propylene glycol and oleic acid (Squillante et al. 1998, PMID 9885297). Otto et al. 2008 (PMID 18832865) found that 10% DMI in oil-in-water emulsions did not significantly enhance permeation of lipophilic actives, attributing the neutral effect to simultaneous solubility enhancement in skin tissue that offsets thermodynamic activity loss in the formulation. DMI has been evaluated as a penetration modifier for hexamidine (Parisi et al. 2016, PMID 27130367) and as a vehicle component in niacinamide delivery (Zhang et al. 2021, PMID 34069268). No dedicated CIR safety assessment was found in the September 2022 QRT or the December 2017/July 2018 QRT. No SCCS opinion was identified.
High-purity glucose-derived solvent with excellent solubilization capacity for poorly water-soluble actives such as retinol, ascorbic acid, and hydroquinone; fully miscible with water and most organic solvents used in cosmetics
Skin penetration enhancement: facilitates delivery of actives into the epidermis without requiring high concentrations of conventional penetration enhancers (alcohols, surfactants); this can improve efficacy of actives at lower doses
Chemical stability enhancer: DMI protects active ingredients susceptible to hydrolysis or transesterification (e.g., ascorbic acid esters, retinoids) by providing a non-protic, relatively anhydrous microenvironment in formulation
Bio-renewable feedstock: derived from D-sorbitol (glucose hydrogenation product), making it compatible with green chemistry and sustainability positioning; low vapor pressure and low irritation potential at typical cosmetic use levels (up to 25%)
Strong skin penetration enhancer: DMI demonstrably traverses the stratum corneum and can co-deliver other actives (including poorly-studied or higher-risk actives) deeper into the epidermis; formulations using DMI at higher concentrations warrant careful evaluation of the overall active ingredient payload
No dedicated CIR safety assessment identified in the QRT as of September 2022: absence from the CIR QRT means no Expert Panel safety conclusion exists for this ingredient under the U.S. CIR framework; safety relies entirely on manufacturer safety data and published literature rather than a formal independent review
Limited cosmetic-specific toxicology literature: published studies focus on formulation performance and delivery enhancement rather than dermal safety endpoints (irritation, sensitization, systemic absorption studies); the absence of adversity data is not the same as demonstrated safety