Mandelic acid was discovered in 1831 by the German pharmacist Ferdinand Ludwig Winckler (1801–1868) while heatingamygdalin, an extract ofbitter almonds, with dilutedhydrochloric acid. The name is derived from theGerman "Mandel" for "almond".[7]
Alternatively, it can be prepared by a substitution reaction from bromophenylacetic acid, as well as byhydrolysis routes starting from various α,α-dihaloacetophenones.[10] It also arises by anisomerization reaction upon heatingphenylglyoxal with various alkalis.[11][12]
Mandelic acid is a substrate or product of several biochemical processes called the mandelate pathway.Mandelate racemase interconverts the two enantiomers via a pathway that involves cleavage of the alpha-CH bond. Mandelate dehydrogenase is yet another enzyme on this pathway.[13] Mandelate also arises from trans-cinnamate viaphenylacetic acid, which ishydroxylated.[14]Phenylpyruvic acid is another precursor to mandelic acid.
Derivatives of mandelic acid are formed as a result of metabolism ofadrenaline andnoradrenaline bymonoamine oxidase andcatechol-O-methyl transferase. Thebiotechnological production of 4-hydroxy-mandelic acid and mandelic acid on the basis ofglucose was demonstrated with a genetically modified yeastSaccharomyces cerevisiae, in which the hydroxymandelate synthase naturally occurring in the bacteriumAmycolatopsis was incorporated into a wild-type strain of yeast, partially altered by the exchange of a gene sequence and expressed.[15]
Mandelic acid can be a component ofchemical face peels analogous to otheralpha hydroxy acids.[2] Mandelic acid is one of the most common chemical components of the "superficial peel" class, which destroy all or part of the epidermis while remaining safe to use on allFitzpatrick skin types.[17][18][19] TheAmerican Academy of Dermatology says there is insufficient evidence to recommend chemical peels (including those with mandelic acid) as a treatment foracne vulgaris.[20] While noting it was widely used in cosmetic products, known to be effective, and frequently prescribed for acne, mandelic acid was among the ingredients not recommended for acne in a 2025Journal of the American Academy of Dermatology literature review's expert panel, because it is rarely covered by insurance and more costly than treatments with similar effects such asvitamin A derivatives.[21]
The drugscyclandelate andhomatropine[23] areesters of mandelic acid.[citation needed] Homatropinedilates eyes foreye exams and wears off quickly.[23] This effect was discovered by chemist Alfred Ladenburg in 1880 and was preferred because the previous mixture caused blurry vision for days. Mandelic acid replacedtropic acid in the synthesis of homatropine.[23][24][25]
Mandelic acid was discovered in 1831 by the German pharmacist Ferdinand Ludwig Winckler (1801–1868) while heatingamygdalin, an extract ofbitter almonds, with dilutedhydrochloric acid. The name is derived from theGerman "Mandel" for "almond".[7]
The short-acting eye dilation effect as part ofhomatropine was discovered by chemist Alfred Ladenburg in 1880. Mandelic acid then replacedtropic acid in the synthesis of homatropine.[31][23][24]
Takeru Higuchi and Roy Kuramoto demonstrated one of the earliest forms of pharmaceuticalcocrystals in studies published during 1954 that involved mandelic acid.[32]
Mandelic acid is moderatelytoxic if ingested.[4][33] It ispoisonous if injected.[33] Frequent absorption can result in kidney irritation.[33] When burning, mandelic acid emits acrid smoke and fumes.[33]
Exposing the white crystal form to light will darken to brown and decompose the crystals over time.[4][5][33]
^Kenyon, George L.; Gerlt, John A.; Petsko, Gregory A.; Kozarich, John W. (1995). "Mandelate Racemase: Structure-Function Studies of a Pseudosymmetric Enzyme".Accounts of Chemical Research.28 (4):178–186.doi:10.1021/ar00052a003.
^Mara Reifenrath,Eckhard Boles:Engineering of hydroxymandelate synthases and the aromatic amino acid pathway enables de novo biosynthesis of mandelic and 4-hydroxymandelic acid with Saccharomyces cerevisiae. Metabolic Engineering 45, Januar 2018; S. 246-254.doi:10.1016/j.ymben.2018.01.001.
^Engström K, Härkönen H, Kalliokoski P, Rantanen J. "Urinary mandelic acid concentration after occupational exposure to styrene and its use as a biological exposure test" Scand. J. Work Environ. Health. 1976, volume 2, pp. 21-6.
^Lee, Kachiu C.; Wambier, Carlos G.; Soon, Seaver L.; Sterling, J. Barton; Landau, Marina; Rullan, Peter; Brody, Harold J. (2019)."Basic chemical peeling: Superficial and medium-depth peels".Journal of the American Academy of Dermatology.81 (2). American Academy of Dermatology:313–324.doi:10.1016/j.jaad.2018.10.079.PMID30550830. RetrievedSeptember 11, 2025.Common superficial peels include glycolic acid (GA), salicylic acid (SA), Jessner solution (JS), retinoic acid, lactic acid, mandelic acid, pyruvic acid (PA), and trichloroacetic acid (TCA) 10% to 35%.
^Shan N, Zaworotko MJ (April 26, 2021). "Polymorphic Crystal Forms and Cocrystals in Drug Delivery (Crystal Engineering), 3.2 Case Studies of Pharmaceutical Cocrystals".Burger's Medicinal Chemistry and Drug Discovery. Wiley.doi:10.1002/0471266949.bmc156.pub2.ISBN978-0-471-26694-5. RetrievedSeptember 11, 2025.Perhaps, the earliest examples of pharmaceutical cocrystals were described in a series of studies conducted in the 1950s by Higuchi and his coworkers (65, 66), who studied complex formation between macromolecules and certain pharmaceuticals; for example, complexes of polyvinylpyrrolidone (PVP) with sulfathiazole, procaine hydrochloride, sodium salicylate, benzylphenicillin, chloramphenicol, mandelic acid, caffeine, theophylline, and cortisone were isolated (65, 66).
This article incorporates text from a publication now in thepublic domain: Chisholm, Hugh, ed. (1911). "Mandelic Acid".Encyclopædia Britannica. Vol. 17 (11th ed.). Cambridge University Press. p. 559.
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