If a person's blood pressure is only mildly elevated (160/100 mm Hg or less), it can often be successfully treated by adopting some lifestyle changes such as stopping smoking, eating a balanced, low-fat, low-salt diet, with lots of fruit, vegetables and grains, restricting caffeine consumption to less than five cups of coffee or tea a day, exercising regularly (30 minutes a day of aerobic exercise such as swimming, jogging or cycling) relaxation therapies, such as meditation and reducing their weight if they are overweight.
For about a third of cases these measures will be enough to return the blood pressure to normal and even achieving a relatively low drop in blood pressure can have significant health benefits - a reduction of 5 mmHg in the diastolic blood pressure will reduce the chances of having a stroke by 34%, and of developing heart disease by 20%.
For others a doctor will prescribe one or more of a wide range of available drugs to lower the blood pressure. These drugs have differing ways of lowering the blood pressure - some relax the heart, while others relax the smooth muscles in the small arteries so they widen and allow blood to pass through more easily.
Usually one drug at low dose is initially prescribed and the dose gradually increased until the blood pressure is brought under control - sometimes, another, or several more drugs will need to be added to bring it under control and finding the best drug, or combination of drugs for a person is a process of trial and error. Sometimes a drug may cause unwanted side effects in people or may have adverse interactions with other drugs and so may need to be discontinued and another drug substituted.
In some cases after a period, the drug can be stopped, and providing the blood pressure remains normal, need not be taken again; it is more common however that the regime will need be continued for life.