Phenolphthalein - Synthesis, Uses, Effects and Precautions - WorldOfChemicals

Toxic Effects of Phenolphthalein


Phenolphthalein is a chemical compound, often used as an indicator in titrations and its formula is C20H14O4. It is a weak acid that is partially soluble in water and is usually dissolved in alcohol for experimental applications. Phenolphthalein molecules are colorless, whereas its ions are pink.



Phenolphthalein is synthesized through condensation of phthalic anhydride with two equivalents of phenol under acidic conditions. It was first synthesized by Adolf von Baeyer in 1871.



Phenolphthalein is commonly used as a chemical indicator, which turns from colorless to pink in the range of 8–10 pH, which makes it ideal for the titration of strong acids, such as hydrochloric acid.

Phenolphthalein is used as a laxative to treat incomplete and infrequent bowel movement. In such cases, it is used to empty the bowels. It is usually administered orally. It is available in the form of an oral solution, oral capsule, oral tablet, wafer and chewing gum.

Phenolphthalein was widely used as a laxative for over a century. However, it is now being removed from the over the counter laxatives due to its concerns revolving around carcinogenicity.


Toxic Effects 

Phenolphthalein has been observed to cause cancers in animals, based on studies. This has raised suspicions over the use of phenolphthalein by humans. However, studies have also shown that phenolphthalein does not increase the risk of getting cancers such as kidney cancer, lymphoma and kidney cancer.

Phenolphthalein has been found to hinder human cellular calcium influx by means of store-operated calcium entry. This is affected by preventing thapsigargin and thrombin, the two activators of SOCE that increase intracellular free calcium.

Other potential effects inflicted on exposure to phenolphthalein are eye irritation, skin irritation, fever from ingestion, increase in blood pressure and respiratory tract irritation.



Phenolphthalein has been included in the European Chemicals Agency's candidate list for Substances of Very High Concern (SVHC). There are precautionary guidelines laid out by OSHA for the use of phenolphthalein.

Regulations alike, ensure that manufacturers of phenolphthalein and other such toxic chemicals are obliged to notify their customers of the presence of any toxic substances, which are of high concern in their chemical products exceeding 0.1% by weight and provide instructions for the safe use of the chemical. 

A material safety data sheet is instrumental in the safe handling of phenolphthalein. This safety sheet lists information such as composition, chemical and physical properties, hazards identification, first aid measures, firefighting measures, accidental measures, handling and storage, exposure controls, personal protection and other vital information. 


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