Propolis is a multifunctional material used by bees in the construction and maintenance of their hives. Use of propolis by humans has a long history, predated only by the discovery of honey. Use of products containing propolis have resulted in extensive dermal contact and it is now increasingly being used a dietary supplement. Unlike many 'natural' remedies, there is a substantive database on the biological activity and toxicity of propolis indicating it may have many antibiotic, antifungal, antiviral and antitumour properties, among other attributes. Although reports of allergic reactions are not uncommon, propolis is relatively non-toxic, with a no-effect level (NOEL) in a 90-mouse study of 1400 mg/kg body weight/day.