Hidden Sodium in Medications Can Raise Blood Pressure, Especially for Those with Heart or Kidney Conditions
Many people diligently watch their salt intake to manage blood pressure, but may be unaware that medications can contain surprisingly high levels of sodium. This “hidden sodium” in drugs could be a significant factor in uncontrolled blood pressure, particularly for individuals with pre-existing heart or kidney conditions, according to pharmacists.
Pharmacist Hung Cheng-hsien points to a medical condition known as “drug-induced hyponatremia” which has two main mechanisms. The first is excessive sodium intake, where the medication itself contains sodium, essentially acting like drinking saltwater. The second is excessive fluid loss, as some medications can cause patients to lose water, concentrating the sodium in the body.
Effervescent tablets – including vitamin C, pain relievers and NAC expectorant formulations – often contain large amounts of sodium bicarbonate to dissolve quickly, increasing the risk. Long-term use of these types of tablets can significantly increase related health risks. Some antibiotic injections contain as much as 100 to 400 milligrams of sodium per dose. Even some antacids, cold syrups, and cough medicines include sodium salts.
Research published in BMJ Open in 2023 analyzed commercially available effervescent dietary supplements in Germany and found that vitamin products had particularly high sodium content, averaging around 400 milligrams per tablet, with some vitamin C effervescent tablets exceeding 560 milligrams. According to Hung Cheng-hsien, the World Health Organization recommends a daily sodium intake of no more than 2000 milligrams, meaning a single effervescent tablet could account for nearly one-third of that limit – not including sodium from meals.
The risks associated with long-term use of effervescent tablets include a more than sevenfold increase in the risk of high blood pressure, a 22% increase in the risk of stroke, a 16% increase in cardiovascular events, and a 28% increase in all-cause mortality, according to studies.
Diuretics, which promote fluid loss, can as well contribute to increased sodium concentration if fluid intake isn’t sufficient. Corticosteroids can disrupt the body’s fluid balance, while antidiuretic hormone antagonists affect the kidneys’ ability to concentrate urine, leading to increased fluid excretion.
The American Heart Association warns that sodium causes the body to retain fluid, increasing the workload on the heart and potentially triggering breathing difficulties or edema. For individuals with chronic kidney disease, especially those with hypertension or proteinuria, excessive sodium intake can accelerate kidney function decline. Those with heart failure should be particularly cautious.
Individuals with hypertension are particularly sensitive to sodium, and may experience unexplained increases in blood pressure after taking medication. Those with cirrhosis may experience increased fluid retention and swelling, while people with diabetes need to strictly control their sodium intake. High-risk pregnant women with high sodium intake are at increased risk of developing pregnancy-induced hypertension, and the elderly are more susceptible to the effects of sodium on blood pressure.
To safely use effervescent tablets, it’s important to check the ingredient list and sodium content before purchasing, control the frequency of use, and choose low-sodium or sodium-free formulations when available. Consulting with a doctor or pharmacist can help individuals assess their risk and choose safer medication options.
