ATC Code D11AX11
Formula C6H6O2
Molar Mass (g·mol−1) 110,1106
Physical State solid
Density (g·cm−3) 1,330
Melting Point (°C) 170-171
Boiling Point (°C) 285-287
PKS Value 9,91
CAS Number 123-31-9
PUB Number 785
Drugbank ID DB09526
Solubility moderate in water


Hydroquinone is an active ingredient with skin-lightening properties and is used in over-the-counter topical products to correct skin discoloration associated with hyperpigmentation disorders (e.g., sun spots, freckles, melasma). It is often used in combination with alpha-hydroxy acids, corticosteroids, retinoids or sunscreens.

Dihydroxybenzene was discovered in 1844 during a dry distillation. Due to several complications during use, such as skin irritation, exogenous discoloration and carcinogenicity, hydroquinone has been banned in cosmetic products in the EU and the UK.



By inhibiting the enzyme tyrosinase, which is involved in the initial step of the melanin pigment biosynthesis pathway, melanin production is downregulated and the skin is depigmented (decolorized). This lightening of the skin is reversible and can be recolored by sunlight.


Hydroquinone is excreted mainly in the urine.


The drug should not be used in case of:

  • Hypersensitivity
  • Non-melanin pigmentation
  • Vitiligo (white spot disease)
  • Skin cancer
  • Acute dermatitis and eczema
  • Bacterial infections
  • During pregnancy and lactation
  • Children under 12 years of age


Side effects

Common unwanted side effects include:

  • Dry skin
  • Allergic skin reactions (redness, (contact) dermatitis)
  • Blue or black discoloration of the skin
  • Increased body hair
  • Thinning of the skin
  • Steroid acne
  • Stretch marks

Toxicological data

As a result of overdose, symptoms may include vomiting, dizziness, shortness of breath, mental confusion, and circulatory shock.

Editorial principles

All information used for the content comes from verified sources (recognised institutions, experts, studies by renowned universities). We attach great importance to the qualification of the authors and the scientific background of the information. Thus, we ensure that our research is based on scientific findings.

Markus Falkenstätter

Markus Falkenstätter

Markus Falkenstätter is a writer on pharmaceutical topics in Medikamio's medical editorial team. He is in the last semester of his pharmacy studies at the University of Vienna and loves scientific work in the field of natural sciences.

Mag. pharm Stefanie Lehenauer

Mag. pharm Stefanie Lehenauer

Stefanie Lehenauer has been a freelance writer for Medikamio since 2020 and studied pharmacy at the University of Vienna. She works as a pharmacist in Vienna and her passion is herbal medicines and their effects.

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