SYMPATHOMIMETIC DRUGS, such as EPHEDRINE and NORADRENALINE, raise the BLOOD PRESSURE temporarily by acting on receptors that constrict peripheral blood vessels. They are occasionally used as a quick way of raising blood pressure when other measures have failed, but they have potentially serious side-effects on the kidney. Vasoconstrictors are also used with local anaesthetics (see under ANAESTHESIA) to counteract the latter's vasodilator effect. Adrenaline will reduce local blood flow, slow the absorption of anaesthetic and prolong its effect.