There are quite literally hundreds of different medications to treat high blood pressure, but many commonly prescribed hypertension drugs can make your skin more sensitive to the sun's rays. Each category of medication has a different mechanism by which it causes sun sensitivity, but they all require that you take special care to avoid sun exposure and be extra careful about using sunscreen and taking other precautions. Ask your doctor or pharmacist if your type of blood pressure medication causes sun sensitivity and how you can protect yourself.

In summer 2011, the website Drugs.com listed 206 different types of antihypertensive, or blood pressure medications, approved for use in the United States. Moreover, the National Heart, Lung and Blood Institute reports that many people take two or more kinds to adequately bring down their blood pressure. Hypertension is a major risk for heart disease. It makes the heart work too hard, and it can weaken your blood vessels. The nine categories of blood pressure medications include diuretics, ACE inhibitors, beta-blockers, angiotensin antagonists, calcium channel blockers, alpha-blockers, alpha-beta-blockers, vasodilators and nervous system inhibitors.

Beta-blockers, vasodilators and diuretics are the most common blood pressure medications that require you to be extra careful in the sun. They can cause photosensitivity, or a negative reaction of your skin when exposed to sunlight or heat. The symptoms can range from mild irritation to itchy rashes up to blisters, scaly, raised patches and burning. The milder reaction may be a photoallergic one, while the more severe reactions might be phototoxic. A report in Toronto's "Globe and Mail" said that the higher your medication dose and the more exposure you have to sunlight, the higher your chances of experiencing photosensitivity.

Diuretics, also called water pills, work in your kidneys to flush out excess water and sodium through urine. Vasodilators relax your blood vessels, and beta-blockers make your heart beat less often and with less force. The chemicals in these medications absorb ultraviolet sun rays as well as radiation. The drugs can set off a reaction with free radicals, which are harmful substances that can be created in your skin as a result of ultraviolet radiation

Johns Hopkins University advises you to avoid direct sunlight, especially between 10 a.m. and 3 p.m. when the sun's rays are at their strongest. Wear protective clothing such as a hat and sunglasses, and use sunblock and lip balm to protect your skin. The university advises against all forms of tanning and the use of sunlamps if you take blood pressure medications. An Australian researcher publishing in the journal "Drug Safety" suggest that a diet rich in antioxidants might also help combat the free radicals associated with some blood pressure medications,.