<p>Avariety of drugs are used to treat hyper-tension. This review will cover four groups of antihypertensives: the commonly used beta-blockers, calcium channel blockers and angiotensin converting enzyme (ACE) inhibitors, plus the newest antihypertensives, angiotensin II antagonists. Box 1 lists the drugs in these groups which are licensed in the UK to treat hypertension. Overdose of beta-blockers or calcium channel blockers can result in significant toxicity, and treatment of drug-induced cardiac effects can be complex. Effects may be resistant to therapy and fatalities from these two groups of drugs have been reported. ACE inhibitors and the related angiotensin II antagonists seem to produce less severe effects in overdose, and treatment is essentially symptomatic and supportive.</p>