High blood pressure, also called hypertension, is one of the most common long-term health conditions around the world. In Australia, more than one in three adults aged 18 years and older have high blood pressure.
Many people do not know they have it because it often causes no obvious symptoms. Over time, however, untreated high blood pressure can damage blood vessels and place extra strain on the heart.
This greatly increases the risk of heart attacks, strokes, heart failure, and kidney disease. For this reason, keeping blood pressure under control is one of the most important ways to protect long-term health.
Doctors often recommend healthy lifestyle changes such as eating less salt, exercising regularly, maintaining a healthy weight, limiting alcohol, and not smoking. However, many people also need daily medicine to keep their blood pressure at a safe level. One of the most commonly prescribed medicines is hydrochlorothiazide.
This drug belongs to a group of medicines called diuretics, sometimes known as “water pills.” It helps the body remove extra salt and water through urine, which lowers blood pressure and reduces the workload on the heart.
Although hydrochlorothiazide has been used safely for many years and helps prevent serious heart and blood vessel problems, researchers continue to study its long-term safety.
A recent study from UNSW Sydney has found evidence that the medicine may increase the risk of certain types of skin cancer in older adults. The possible link is important because hydrochlorothiazide can make the skin more sensitive to sunlight. This increased sensitivity may allow more damage from ultraviolet, or UV, rays, which are a major cause of skin cancer.
To investigate the possible risk, the researchers analyzed health information provided by the Department of Veterans’ Affairs. The data included anonymous records of medicine use, hospital visits, and cancer diagnoses among healthcare cardholders aged 65 years and older living in New South Wales. The study covered the years from 2004 to 2015.
The research team compared people who had developed skin cancer with similar people who had not. They studied 45 people diagnosed with squamous cell cancer of the lip and 659 people diagnosed with malignant melanoma, the most dangerous form of skin cancer. These patients were compared with more than 13,300 people who did not have these cancers.
The results showed that people taking hydrochlorothiazide had a higher chance of developing both malignant melanoma and squamous cell lip cancer. The researchers also found that the risk of lip cancer increased the longer the medicine was used. This suggests that long-term exposure to hydrochlorothiazide may increase the harmful effects of sunlight on the skin.
Even with these findings, the researchers strongly advise patients not to stop taking hydrochlorothiazide on their own. High blood pressure remains a serious medical condition, and suddenly stopping treatment may increase the risk of heart attack or stroke.
Anyone with concerns about their medicine should speak with their doctor before making any changes.
Instead, the researchers recommend taking practical steps to lower skin cancer risk while continuing treatment when appropriate. Regular skin examinations can help detect suspicious changes early, when skin cancer is often easier to treat.
Patients should also protect themselves from the sun by using sunscreen, wearing hats and protective clothing, seeking shade, and avoiding strong sunlight during the middle of the day whenever possible.
Because of the growing evidence, prescribing information for hydrochlorothiazide has been updated to include this possible skin cancer risk. This change helps doctors and patients make informed decisions by weighing the proven benefits of controlling blood pressure against the small but important possibility of long-term side effects.
The findings also support several earlier international studies that reported similar links between hydrochlorothiazide and skin cancer.
Together, these studies show why medicines should continue to be monitored even after they have been approved for use. Long-term research involving large groups of patients can identify uncommon side effects that may not appear during the original clinical trials.
The study was led by Dr. Benjamin Daniels and his team at UNSW Sydney and was published in the journal Basic & Clinical Pharmacology & Toxicology. The research provides valuable new information that may help doctors better protect patients while continuing to effectively treat high blood pressure.
If you care about high blood pressure, please read studies that early time-restricted eating could help improve blood pressure, and natural coconut sugar could help reduce blood pressure and artery stiffness.
For more information about blood pressure, please see recent studies about How to eat your way to healthy blood pressure and results showing that Modified traditional Chinese cuisine can lower blood pressure.
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