TORONTO Health Canada says prolonged use of a drug commonly prescribed for high blood pressure could increase a person's risk of developing non-melanoma skin cancer.

Hydrochlorothiazide is a diuretic, or water pill, that is also prescribed to reduce fluid retention related to heart failure and some kidney and liver problems.

A safety review by Health Canada found that taking the medication can make skin more sensitive to ultraviolet radiation from sunlight and tanning equipment.

The review of research evidence suggests patients taking the drug for more than three years could have at least a fourfold higher risk of developing non-melanoma skin cancer.

However, Health Canada says that because of limitations in the studies, such as a lack of patient data on sun exposure and severity, there is uncertainty regarding the findings.

Even so, people taking hydrochlorothiazide are advised to limit UV exposure and to seek medical attention if they identify new skin lesions or changes in moles.

The federal department says doctors should consider alternative medications for patients with an elevated risk of non-melanoma skin cancer, including those with fair skin or a personal or family history of skin cancer.