Allantoin is a kind of urea-based hydantoin. Pathological observation of the effect of urea on skin showed that the main changes were degeneration of cuticle, regional swelling and thickening of cuticle, edema and cracks in epidermal spine cells, and mild degeneration of dermal collagen fibers, which indicated that allantoin had the effect of dissolving and degenerating cuticle and increasing skin moisture. The water uptake capacity of the epidermis cuticle mainly depends on the electron-dense matrix of the conjugate of non-keratin, which connects keratinocytes, while keratin itself has less effect on the whole skin humidity.

Allantoin moisturizes the skin because it can increase and promote the hydration ability of the conjugate matrix, and also act on keratin to increase its ability to bind water, making the skin smooth, moist and flexible. Paper-layer analysis of allantoin and aluminium hydroxylallantoic acid in vitro showed that allantoin and aluminium hydroxylallantoic acid could relax normal and pathological cuticle, release water of soluble non-keratin and more free amino acids. The urea part of allantoin also has antifungal and antibacterial effects. It was reported that 2%, 5% and 10% urea could inhibit the growth of gypsum-like tinea and flocculent epidermal tinea in tubes, and that 10% to 60% urea could inhibit the growth of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The hydantoin part of allantoin is similar to barbituiritacid and has analgesic, anaesthetic and anti-irritant effects. Because it neutralizes and detoxifies irritants and soothes the skin, it is considered to have anti-irritant and anaesthetic effects. Allantoin is also a derivative of uric acid, experimental and clinical. Studies have shown that it has the effects of keratolysis, hydration, anesthesia and analgesia, anti-irritants, promoting epithelial growth, anti-inflammatory, bacteriostasis and so on. In 1937, Kaplan used allantoin to treat chronic surgical ulcers. It was found that allantoin had significant effects on necrotic tissue, granulation tissue growth and wound healing. In 1962, Cahen and his colleagues first used allantoin hydroxyaluminate to treat gastric ulcers in experimental animals and achieved remarkable results. Later, there were many reports of satisfactory clinical effects in Europe and the United States, especially in Japan. In 1976, the newly developed compound allantoin tablets in China were used for gastric and duodenal ulcers with good curative effect.

At present, allantoin is widely used in dermatology clinic as an external preparation, which provides a new and effective way for the treatment of chapped hands and feet, ichthyosis, psoriasis, various keratodermatosis, wound expansion and cleaning, and peptic ulcer. If 2% allantoin is used to treat follicular keratosis, palmoplantar keratoderma and exfoliative keratolysis, the curative effect is better than 30% urea. 46 cases of ichthyosis and keratodermatosis were treated with 1% allantoin cream compared with 6101 cream. The results showed that 1% allantoin cream was better than 6101 cream, while 0.1% retinoic acid cream or ointment had no effect on ichthyosis. In addition, according to Japanese patent reports, allantoin is used as an important component of diabetes, cirrhosis and cancer therapeutics, and can also be used to treat osteomyelitis.