If you or a loved one has been prescribed hydrochlorothiazide, you may want to be extra vigilant about checking for skin changes. That’s because long-term use of this common diuretic has been previously linked to lip and non-melanoma cancers, but a new study may also extend those increased risks to melanoma.
“We have recently shown that hydrochlorothiazide use increases the risk of lip and nonmelanoma skin cancer, notably squamous cell carcinoma,” the authors wrote in JAMA Internal Medicine. “It would have substantial implications if the carcinogenic effect of hydrochlorothiazide also extended to malignant melanoma.”
In the U.S., an estimated 10 million people are prescribed hydrochlorothiazide annually for things like high blood pressure, swelling of the extremities (edema), osteoporosis, and diabetes. Keep in mind while you’re reading the rest of this post, the usual dosage is 25 mg or higher. (I’ll explain why in a minute.)
This study looked at people who have a high usage of this medication. And for the purposes of the study, that meant those with a cumulative dose of 50,000 mg or more. So for the average daily dose of 25 mg, someone who has been on this medication for about 5.5 years would fall into the “high dosage” population. As many of you know, if you have high blood pressure and/or Type 2 diabetes unless you make radical changes to your diet and exercise regime (and even then that might not be enough because there seems to be a hereditary component to hypertension and diabetes), you may be on the medication for decades.
A result of the study is those high dosage users of hydrochlorothiazide appeared to have a higher risk of being diagnosed with melanoma as compared to people who have never used it. And the types of melanoma diagnosed? Lentigo and nodular melanoma…
The study’s authors wrote: “The findings for melanoma subtype are somewhat surprising, as lentigo and superficial spreading melanoma are known to be associated with high sun exposure, whereas the etiology of nodular melanomas is less elucidated. It is worrying that hydrochlorothiazide use appears to be associated with an increased risk of melanoma, and the particular associations observed for lentigo melanoma and nodular melanoma warrant further research.”
The researchers looked at 19,273 melanoma cases diagnosed over 11 years (2004-2015; 12,494 superficial spreading subtype, 1,465 nodular, and 386 lentigo). And then they matched them with a control group of 192,730 people who had no history of HIV or cancer (with the possible exception of nonmelanoma skin cancer), and had never used the medication. What they found is that 2.1% of the high usage hydrochlorothiazide users presented with melanoma versus 1.8% of the control group. While that seems small, it is significant (because statistics was not my best class, I’ll refrain from trying to explain why it’s significant, just know that it is…).
The researchers then looked at other common hypertension medications but did not find the same increase in melanoma development. What is interesting is that the same research group showed in a previous study the use of hydrochlorothiazide was associated with an increased risk of squamous cell carcinoma of the lip, with the increased risk coming at cumulative doses of 25,000 mg or higher.
So, what does that mean? Basically, if you or someone you know is taking a maintenance regimen for high blood pressure, edema, osteoporosis, or diabetes, you may want to check to see if hydrochlorothiazide is their prescribed medication. If so, regular annual skin exams are critically important and it may be wise to let the dermatologist know about this medication usage.