Slow, time-dependent, irreversible, highly selective inhibitors of COX-2 such as celecoxib, etoricoxib, rofecoxib and valdecoxib, so-called coxibs, are a new group of drugs widely used in rheumatology as well as in other fields of medicine. The tolerability of these drugs is at least equivalent to that of commonly used non-selective COX inhibitors (e.g. diclofenac, ibuprofen, naproxen). The unquestionable superiority of selective COX-2 blockade includes a low risk of gastrointestinal side effects. However, similarly to the other COX inhibitors, coxibs must be carefully administered to patients with coexistent liver and renal disease, generalised atherosclerosis, ischaemic heart disease, and to the elderly and children. Pregnancy and lactation require precise monitoring of adverse effects on the fetus, neonate and infant, or discontinuation of therapy with the drug.