Both caffeine and theophylline have a variety of roles in regulating inflammatory responses. At pharmacologically relevant concentrations most of the effects of these commonly used methylxanthines are attributable to adenosine receptor blockade and histone deacetylase activation. In addition, at higher concentrations methylxanthines can suppress inflammation by inhibiting phosphodiesterases, thereby elevating intracellular cyclic adenosine monophosphate levels. In summary, methylxanthines regulate inflammation by multiple mechanisms.