<p>Atenolol and Chlorthalidone combination may potentiate the action of other antihypertensives such as Clonidine, Diltiazem. Prostaglandin synthase inhibiting drugs e.g. Indomethacin may decrease the hypotensive effects of beta-blockers. This tablet should not be given with Lithium due to high risk of Lithium toxicity.</p>