Sunlight, medications and health

Thiazide is the most commonly prescribed anti-hypertensive medications around the world. The recent data shows that accumulation dosage of thiazide for six years leads to skin cancer. Thiazide causes hyper uric acid levels, high calcium levels; it raises levels of blood glucose and cholesterol. And now there is additional one on the list, skin cancer. The reason is that thiazide photosensitizes the skin, especially in the light colored people. This will probably change the guideline for hypertension treatment in the coming years. At least for now, I strongly advise patient with other risk factors for skin cancer, show avoid photosensitizing medications.

Photosensitivity and photoallergy.

A handful of medications have been recognized for decades as causing photosensitivity. However, the photosensitivity is more than photoallergy that manifests as skin eruption, rashes, itchiness or tingling in the sun exposed area. These photoallergy reactions are different from the carcinogenic effects that were recently identified. In terms of photoallergy, Tetracycline, doxycycline, nalidixic acid, voriconazole, amiodarone, hydrochlorothiazide, naproxen, piroxicam, chlorpromazine and thioridazine are among the most commonly implicated medications.

Sunlight exposure.

Regarding the correlation between photoallergy and carcinogenic photosensitivity, there are many potential mechanisms that are beyond the discussion of selection of antihypertensive treatment. Human body, as part of the nature, lives in harmony with the surroundings that includes the sunlight. Enough and moderate exposure is indispensible for both mental and physical health. However, when the harmony is disrupted by the external factors such as therapeutics, pathological conditions arises even though the objective blood pressure is achieved.

About hypertension treatment.

In terms of hypentensive treatment, whether or not we should follow the medication guideline should be considered medically on a case-by-case basis. Genetic background, lifestyle, work and family dynamics, personal coping skills over stress, comorbidities are all in the scope of consideration.


1.     Drucker AM, Rosen CF. Drug-induced photosensitivity: culprit drugs, management and prevention. Drug Saf. 2011;34:821-837. Abstract
2.     Kunisada M, Masaki T, Ono R, et al. Hydrochlorothiazide enhances UVA-induced DNA damage. Photochem Photobiol. 2013;89:649-654. Abstract
3.     Pottegård A, Hallas J, Olesen M, et al. Hydrochlorothiazide use is strongly associated with risk of lip cancer. J Intern Med. 2017;282:322-331. Abstract
4.     Pedersen SA, Gaist D, Schmidt SA, Hölmich LR, Friis S, Pottegård A. Hydrochlorothiazide use and risk of nonmelanoma skin cancer: a nationwide case-control study from Denmark. J Am Acad Dermatol 2018;78:673-681

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