What it is
Methylparaben is the methyl ester of para-hydroxybenzoic acid, with the formula C8H8O3, appearing as colorless crystals or a white powder. In cosmetics it is added as a preservative so the formula does not spoil, helping protect against microbial growth, with parabens being particularly noted for anti-fungal action. It is valued because it is inexpensive, colorless, odorless, stable, and readily biodegraded, and it is often used together with other parabens to broaden coverage. The same compound is designated E218 in food labeling and is also used to preserve pharmaceuticals.
Safety & warnings
Methylparaben is one of the most studied cosmetic preservatives; it is readily absorbed and rapidly excreted in urine without accumulating in the body, and it has a long record of use. It is generally well tolerated, and ingredient references describe contact allergy to it as uncommon in normal use. One laboratory study reported that methylparaben-treated skin cells fared worse than untreated cells after sun exposure, which is one reason daily sunscreen use is sensible regardless of paraben content. People with a known paraben allergy should avoid it.
Origin & sourcing
Methylparaben occurs in nature, including as a component of insect pheromones such as the queen bee mandibular pheromone, and it can be synthesized for commercial use. Parabens are produced by esterifying para-hydroxybenzoic acid with the appropriate alcohol; for methylparaben that alcohol is methanol. The para-hydroxybenzoic acid starting material is made by a modification of the Kolbe-Schmitt reaction using potassium phenoxide and carbon dioxide.
History
Parabens were discovered in the late 19th century and have been used widely as preservatives in cosmetics, pharmaceuticals, and foods since the 1920s, becoming popular for their reliable antimicrobial action without altering product stability or sensory properties. A 1994 European Scientific Committee for Food review concluded that parabens were essentially non-toxic, non-carcinogenic, and non-genotoxic.
Questions everyone asks
What does methylparaben do in a product?
It is a preservative that protects the formula from microbial spoilage, and it is especially effective against fungi.
Is methylparaben natural?
It occurs naturally, for example in some insect pheromones, but the methylparaben used in products is typically synthesized by esterifying para-hydroxybenzoic acid with methanol.
Why is methylparaben often paired with other parabens?
Different parabens cover different microbes and solubilities, so combining methylparaben with others broadens overall preservative coverage.