Are there any dangers associated with the use of allantoin in cosmetic products?

In its pure form, theallantoin appears as a white and odourless powder. It is found in many plants such as comfrey, horse chestnut, and bearberry. Comfrey is traditionally used for its healing, regenerative and soothing properties. The content of allantoin in the root varies between 0.7 and 2.5%.

Allantoin is also naturally present in animals, particularly in the urine and amniotic fluid of mammals, but also in snail slime. For mammals, it results from the oxidation of uric acid and is produced in a similar way for cosmetic care. Allantoin can also be of synthetic origin. Its chemical molecule possesses the same virtues as that obtained naturally. The chemical synthesis of allantoin is possible through an oxidation reaction of uric acid.

This is a coveted active ingredient for its healing, keratolytic and soothing properties. Being naturally hydrating, it helps to strengthen the skin's hydrolipidic film, to limit transepidermal water loss, and to give the skin suppleness and softness. Its soothing properties also allow it to combat inflammation and skin irritations. It is also capable of regenerating the skin by promoting the elimination of dead cells from the epidermis, leaving the skin soft.

Theallantoin is suitable for all skin types, especially if they are sensitive, irritated, damaged and sun-damaged. It is generally used in skincare in the form of cream, balm, lotion and sunscreen at 0.5 to 1% of the total weight.

Owing to its hydrating and softening properties, allantoin is considered safe for skin care. The United States Food and Drug Administration (FDA) has listed allantoin as asafe and effective agent for skin protection at concentrations of 0.1 to 2%. In Europe, this active ingredient is not regulated for its use in cosmetic care. It is considered non-toxic, non-allergenic, and non-irritating, in addition to being suitable for all skin types, even delicate and reactive epidermis. Finally, an Ames test has demonstrated that allantoin is not a mutagenic compound.

A safety study has reported that no adverse effects are associated with allantoin when it is used in accordance with the instructions on the label. However, it is not ruled out that topical treatments may cause irritation or an allergic reaction, especially if they contain other ingredients. As a precaution, it is recommended to perform a skin test in the crook of the arm to observe if a potential allergic reaction occurs. It is better to stop using a skincare product containing allantoin if one or more of the following reactions occur: inflammation, redness or discolouration of the skin, dryness, itching or hives.

• BECKER L. C. & al. Final report of the safety assessment of allantoin and its related complexes. International Journal of Toxicology (2010).

  SAVIĆ V. L. & al. Comparative study of the biological activity of allantoin and aqueous extract of the comfrey root. Phytotherapy Research (2015).