Benzoyl peroxide

Benzoyl peroxide
IUPAC name
dibenzoyl peroxide
Other names
Benzoyl peroxide (BPO)


Dibenzoyl peroxide (DBPO)
94-36-0 YesY
3D model (Jmol) Interactive image
ChEMBL ChEMBL1200370 N
ChemSpider 6919 YesY
ECHA InfoCard 100.002.116
EC Number 202-327-6
E number E928 (glazing agents, ...)
KEGG D03093 YesY
PubChem 7187
RTECS number DM8575000
Molar mass 242.23 g·mol−1
Appearance colourless solid
Density 1.334 g/cm3
Melting point 103 to 105 °C (217 to 221 °F; 376 to 378 K) decomposes
D10AE01 (WHO) QD11AX90 (WHO)
Main hazards irritant, explosive[1]
Safety data sheet See: data page
E (E)
Xi (Xi)
R-phrases R3, R7, R36, R43
S-phrases (S2), S3/7, S14, S36/37/39
NFPA 704
Flash point 80 °C; 176 °F; 353 K[1]
80 °C (176 °F; 353 K)
Lethal dose or concentration (LD, LC):
7710 mg/kg (mouse, oral)[2]
7000 mg/m3 (mouse, 4 hr)[2]
US health exposure limits (NIOSH):
PEL (Permissible)
TWA 5 mg/m3[1]
REL (Recommended)
TWA 5 mg/m3[1]
IDLH (Immediate danger)
1500 mg/m3[1]
Supplementary data page
Refractive index (n),
Dielectric constantr), etc.
Phase behaviour
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

Benzoyl peroxide (BPO) is an organic compound in the peroxide family. It consists of two benzoyl groups bridged by a peroxide link. Its structural formula is (C6H5CO)2O2. It is one of the most important organic peroxides in terms of applications and the scale of its production. Benzoyl peroxide is used as an acne treatment, for bleaching flour, hair and teeth, for cross-linking polyester resins, and for many other purposes.

It is on the World Health Organization's List of Essential Medicines, the most important medications needed in a basic health system.[3]


Most benzoyl peroxide is used as a radical initiator to induce polymerizations.[4] Other major applications include its antiseptic and bleaching properties.

Acne treatment

Tube of a water-based 5% benzoyl peroxide preparation for the treatment of acne.

Benzoyl peroxide (BPO) is effective for reducing the number and severity of acne lesions. BPO has a bactericidal effect on Propionibacterium acnes bacteria associated with acne and does not induce antibiotic resistance.[5][6] It may be combined with salicylic acid, sulfur, erythromycin or clindamycin (antibiotics), or adapalene (a synthetic retinoid). Two common combination drugs include benzoyl peroxide/clindamycin and adapalene/benzoyl peroxide, an unusual formulation considering most retinoids are deactivated by peroxides. Combination products such as benzoyl peroxide/clindamycin and benzoyl peroxide/salicylic acid appear to be slightly more effective than benzoyl peroxide alone for the treatment of acne lesions.[6]

Benzoyl peroxide for acne treatment is typically applied to the affected areas in gel or cream form, in concentrations of 2.5% increasing through 5.0%, and up to 10%.[5] No strong evidence supports the idea that higher concentrations of benzoyl peroxide are more effective than lower concentrations.[5]

Benzoyl peroxide commonly causes initial dryness and sometimes irritation, although the skin develops tolerance after a week or so. A small percentage of people are much more sensitive to it and liable to suffer burning, itching, crusting, and possibly swelling.[7] It is sensible to apply the lowest concentration and build up as appropriate. Once tolerance is achieved, increasing the quantity or concentration and gaining tolerance at a higher level may give better subsequent acne clearance.[8] Irritation can also be reduced by avoiding harsh facial cleansers and wearing sunscreen prior to sun exposure.[8]

Other uses

Other common uses for benzoyl peroxide include

In the U.S., the typical concentration for benzoyl peroxide is 2.5% to 10% for both prescription and over-the-counter drug preparations that are used in treatment for acne. Higher concentrations are used for hair bleach and teeth whitening. Benzoyl peroxide, like most peroxides, is a powerful bleaching agent. Contact with fabrics or hair can cause permanent color dampening almost immediately. Even secondary contact can cause bleaching; for example, contact with a towel that has been used to wash off benzoyl peroxide-containing hygiene products.[11]

Side effects

Concentrated benzoyl peroxide is potentially explosive[12] like other organic peroxides, and can cause fires without external ignition. The hazard is acute for the pure material, so the compound is generally used as a solution or a paste. For example, cosmetics contain only a small percent of benzoyl peroxide and pose no explosion risk.

The carcinogenic potential of benzoyl peroxide has been investigated. A 1981 study published in the journal Science found that although benzoyl peroxide is not a carcinogen, it does promote cell growth when applied to an initiated tumor. The study concluded, "caution should be recommended in the use of this and other free radical-generating compounds".[13]

In a 1977 study using a human maximization test, 76% of subjects acquired a contact sensitization to benzoyl peroxide. Formulations of 5% and 10% were used.[14]

The U.S. National Institute for Occupational Safety and Health has developed criteria for a recommended standard for occupational exposure to benzoyl peroxide.[15]

Synthesis, structure and physical properties

Benzoyl peroxide was the first organic peroxide prepared by intentional synthesis. It was prepared by treating benzoyl chloride with barium peroxide,[16] a reaction that probably follows this equation:

2 C6H5C(O)Cl + BaO2 → (C6H5CO)2O2 + BaCl2

Benzoyl peroxide is usually prepared by treating hydrogen peroxide with benzoyl chloride.

2 C6H5COCl + H2O2 + 2 NaOH → (C6H5CO)2O2 + 2 NaCl + 2 H2O

The oxygen–oxygen bond in peroxides is weak. Thus benzoyl peroxide readily undergoes homolysis (symmetrical fission), forming free radicals:

(C6H5CO)2O2 → 2 C

The symbol indicates that the products are radicals; i.e., they contain at least one unpaired electron. Such species are highly reactive. The homolysis is usually induced by heating. The half-life of benzoyl peroxide is one hour at 92 °C. At 131 °C, the half-life is one minute.[17]

Benzoyl peroxide breaks down in contact with skin, producing benzoic acid and oxygen, neither of which is significantly toxic.[18]


  1. 1 2 3 4 5 "NIOSH Pocket Guide to Chemical Hazards #0052". National Institute for Occupational Safety and Health (NIOSH).
  2. 1 2 "Benzoyl peroxide". Immediately Dangerous to Life and Health. National Institute for Occupational Safety and Health (NIOSH).
  3. "WHO Model List of EssentialMedicines" (PDF). World Health Organization. October 2013. Retrieved 22 April 2014.
  4. Klenk, Herbert; Götz, Peter H.; Siegmeier, Rainer; Mayr, Wilfried (2005), "Peroxy Compounds, Organic", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a19_199
  5. 1 2 3 Simonart, T. (December 2012). "Newer approaches to the treatment of acne vulgaris". Am. J. Clin. Dermatol. 13 (6): 357–64. doi:10.2165/11632500-000000000-00000. PMID 22920095.
  6. 1 2 Seidler, E. M.; Kimball, A. B. (July 2010). "Meta-analysis comparing efficacy of benzoyl peroxide, clindamycin, benzoyl peroxide with salicylic acid, and combination benzoyl peroxide/clindamycin in acne". J. Am. Acad. Dermatol. 63 (1): 52–62. doi:10.1016/j.jaad.2009.07.052. PMID 20488582.
  7. "Benzoyl peroxide". Mayo Clinic. January 1, 2016.
  8. 1 2 Alldredge, Brian K., ed. (2013). Applied Therapeutics: The Clinical Use of Drugs (10th ed.). Baltimore: Wolters Kluwer Health/Lippincott Williams & Wilkins. p. 949. ISBN 978-1609137137.
  10. Stevens, Cynthia. "Oxy10 for vinyl stains. Benzoyl Peroxide removes stain from Vinyl. Restore Dolls". Prilly Charmin Dolls. Retrieved 9 February 2015.
  11. Bojar, R. A.; Cunliffe, William; Holland, K. T. (1995), "The short-term treatment of acne vulgaris with benzoyl peroxide: effects on the surface and follicular cutaneous microflora.", Br. J. Dermatol., 132: 204–8, doi:10.1111/j.1365-2133.1995.tb05014.x, PMID 7888356
  12. Cartwright, Hugh (17 March 2005). "Chemical Safety Data: Benzoyl peroxide". Oxford University. Retrieved 13 August 2011.
  13. "Skin tumor-promoting activity of benzoyl peroxide, a... [Science. 1981] - PubMed - NCBI". 2012-05-24. Retrieved 2012-09-08.
  14. Leyden, James J.; Kligman, Albert M. (1977), "Contact sensitization to benzoyl peroxide", Contact Dermatitis, 3 (5): 273–75, doi:10.1111/j.1600-0536.1977.tb03674.x
  15. "Criteria for a Recommended Standard: Occupational Exposure to Benzoyl Peroxide (77-166)". CDC - NIOSH Publications and Products. June 6, 2014. Retrieved 2016-07-15.
  16. Brodie, B. C. (1858), "Ueber die Bildung der Hyperoxyde organischer Säureradicale" [On the Formation of the Peroxides of Organic Acid Radicals], Justus Liebigs Ann. Chem., 108: 79–83, doi:10.1002/jlac.18581080117
  17. Li, Hui, III (1998). "Chapter 2". Synthesis, Characterization and Properties of Vinyl Ester Matrix Resins (PDF) (Ph.D.). University of Vermont.
  18. Benzoyl peroxide (PDF), SIDS Initial Assessment Report, Geneva: United Nations Environment Programme, April 2004
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