HCTZ and light sensitivity

Q: For about two decades, I took the diuretic hydrochlorothiazide (HCTZ) to prevent recurring kidney stones. I’d had five years in a row dealing with these stones. Changing my diet and increasing my fluid intake didn’t help, but the drug did.

A Danish study came out noting an increased skin cancer risk from HCTZ. My basal cell carcinoma and squamous cell carcinoma lesions were removed eight years into taking this drug. The melanoma lesion on my scalp appeared the following year. By then, it had spread to my lungs and bones. When the study came out, my oncologist discontinued the HCTZ. This was many years into my cancer journey, though. Luckily, I am in my second remission with immunotherapy every three weeks for the past five years.

A: Thiazide diuretics like HCTZ are taken by more than 20 million Americans on a daily basis. They are perceived as extremely safe medications for high blood pressure. In addition, they are prescribed to lower the risk of recurrent kidney stones.

You have identified a worrisome complication, though. These drugs make skin more sensitive to ultraviolet light, so sunburn is more likely. Researchers have detected an association between HCTZ and skin cancer (Journal of the American Academy of Dermatology, April 2018).

The link with melanoma is controversial. That said, people taking this diuretic should avoid direct sun exposure and ask a dermatologist to check their skin on a regular basis.