Blood pressure drug linked to higher risk of Side Effects, study finds

A widely prescribed drug for high blood pressure may carry greater risks than previously
thought, according to new research.
Scientists at Columbia University examined the long-term use of chlorthalidone, a
diuretic often favored by doctors for its effectiveness in lowering blood pressure. Their
findings, published after reviewing the health records of more than 730,000 patients
over 17 years, suggests the medicine may be linked to a significantly higher risk of side
effects compared with a similar drug, hydrochlorothiazide.

Chlorthalidone and hydrochlorothiazide belong to the same family of medications and
are commonly used to reduce the risk of strokes and heart attacks in patients with
hypertension. But researchers found that patients on chlorthalidone were more than
three times as likely to develop hypokalaemia – a condition caused by dangerously low
potassium levels. Around 6.3% of patients taking chlorthalidone experienced the
condition, compared with 1.9% of those on hydrochlorothiazide.

Low potassium can cause muscle weakness, fatigue, and, in severe cases, life-
threatening irregular heart rhythms. The study also indicated higher risks of kidney
damage and disturbances in electrolytes among chlorthalidone users.

The findings raise questions about long-standing prescribing practices. For years,
chlorthalidone has been considered the more powerful of the two drugs in reducing
blood pressure and preventing cardiovascular events, and many clinicians regarded it
as the superior option. But the Columbia team’s analysis suggests the trade-off in side
effects may be greater than assumed.

“These results don’t mean chlorthalidone should be abandoned altogether,” the
researchers said. “But they do suggest the need for closer monitoring of patients,
especially those already at risk of electrolyte imbalance or kidney complications.”
Hypertension affects millions worldwide and remains one of the leading risk factors for
heart disease, stroke, and kidney failure. Alongside medication, doctors continue to
stress lifestyle changes such as reducing salt intake, exercising regularly, and avoiding
smoking and excess alcohol.

The study underscores the complexity of long-term drug management in chronic
conditions. While both chlorthalidone and hydrochlorothiazide remain effective in
lowering blood pressure, the balance between efficacy and safety may now come under
renewed scrutiny.

For patients already on chlorthalidone, experts advise against abrupt discontinuation.
Instead, they recommend discussing concerns with a doctor and ensuring regular
check-ups to monitor for possible side effects.