Psoriasis is an autoimmune disease that causes the skin to overproduce skin cells and causes a scaly rash to appear. Having psoriasis also increases your risk of developing high blood pressure, which can lead to stroke or heart attack.
A link between psoriasis and high blood pressure was identified in the 1970's. Scientists aren't sure what causes the connection, but some of the theories include the following:
- Those with psoriasis may be prone to developing constricted blood vessels, which can lead to high blood pressure.
- People with psoriasis can have a higher level of endothelin I, a protein which constricts blood vessels and can increase blood pressure.
- The inflammatory properties of psoriasis affect and cause damage to the blood vessels and heart.
There is also research showing "psoriasis patients who have hypertension are more likely to have more difficult-to- control hypertension and require a greater number of anti-hypertensive medications"  than those without psoriasis. The authors of the study said they hoped that the research would alert doctors to the risks of hypertension in patients with psoriasis as well as make them aware of the possible need for a more aggressive approach to treating the hypertension.
The World Health Organization agrees. It recommended that health care professionals routinely screen patients with psoriasis for high blood pressure. According to the president of the International Federation of Psoriasis Associations (IFPA), "Healthcare professionals need to recognize the elevated risk that people with psoriasis carry for developing high blood pressure and include regular tests for hypertension and other known risk factors of cardiovascular disease for this patient group. There are studies indicating that treating psoriasis early and efficiently lowers the risk for co-morbid conditions, such as high blood pressure, and this needs to be taken into account when developing a treatment regimen for an individual with psoriasis." 
Besides high blood pressure, those with psoriasis have an increased risk of other health conditions. A study completed in 2010 and published in the Archives of Dermatology show that having psoriasis can double your risk of having metabolic syndrome - a group of risk factors that increase your risk of heart disease and diabetes. To be diagnosed with metabolic syndrome, you must have three of the following:
- A large waistline
- High triglyceride levels
- Low HDL cholesterol levels (the good cholesterol)
- High blood pressure
- High fasting blood sugar
Having one of the above increases your risk for heart disease and the more of these you have, the more you are at risk for developing it. Making lifestyle changes, such as losing weight, eating a healthy diet and exercising, can prevent, delay or improve metabolic syndrome.
High blood pressure medications
Some medications to treat high blood pressure have the potential to worsen psoriasis. According to the National Psoriasis Foundation, the medication Inderal worsens psoriasis in about 25 percent of people with psoriasis. The foundation lists only this anti-hypertensive medication as worsening psoriasis but says, "It is not known if all high blood pressure (beta-blocker) medications worsen psoriasis, but they may have that potential." 
Because high blood pressure can be dangerous - leading to stroke or heart attack - it is important to work closely with your doctors to find the right medication, or combination of medications, to control your hypertension without causing your psoriasis to worsen.
 "Psoriasis and Hypertension Severity: Results from a Case-Controlled Study," 2011, Feb. 25, April W. Armstrong et al, PLoSONE.org
 "Psoriasis Causes and Known Triggers," Date Unknown, Staff Writer, National Psoriasis Foundation
 "Psoriasis Increases Risk of High Blood Pressure," 2013, April 11, Kelly Fitzgerald, Medical News Today "What is Metabolic Syndrome," 2011, Nov. 3, Staff Writer, National Institutes of Health