In the past, corticosteroids were given to head-injured patients in order to prevent secondary brain damage, even if clinical trials had been inconclusive and potential risks of complications were of concern. Recently, CRASH, a large, multi-centre study on short-term, high-dose corticosteroid treatment in head trauma, was interrupted after enrolling > 10,000 patients because corticosteroid treatment was associated with significantly higher mortality within two weeks. Participating clinicians were not requested to judge the causes of death, but rates of infections and gastrointestinal haemorrhages did not differ between treated patients and controls. Other potential corticosteroid complications include metabolic derangements (particularly hyperglycaemia), adrenal insufficiency and critical illness myopathy. Furthermore, experimental data suggest that corticosteroids may have some harmful effects on neural tissue. In this review, the potential risks of treating head-injured patients with corticosteroids are examined.