Allantoin may be derived from animals but it can also be vegan.
The organization People for the Ethical Treatment of Animals (PETA) has listed this substance in their Animal-derived Ingredients List. PETA writes that allantoin can be derived from the urine of most mammals, for example cows, but it can also be extracted from plants, especially from comfrey.
No matter how this ingredient is sourced, vegan or non-vegan, it is often named the same. To know if the product is free from animal biological parts, look for “vegetarian” or “vegan” stamps on the product or in the product description. In some cases you may even have to ask the manufacturer to know how the ingredient is sourced.