Dissolvable painkillers might bring rapid relief, but researchers are warning many of them also come with a hidden and hearty dose of salt.
For each half a gram of paracetamol, or acetaminophen, that comes in a dissolvable tablet, you may also swallow around 0.4 grams of sodium, one of the main components of salt.
Sodium is often added to drugs to help them disintegrate in water; this allows the body to absorb the medicine faster than by swallowing a pill. But if the maximum daily dose of dissolvable paracetamol is taken, a person can easily exceed the two grams of salt recommended in the diet per day.
Even for those without high blood pressure, a population-based study in the United Kingdom suggests all that extra sodium can take a toll on the body, especially the cardiovascular system.
The research sought to mimic a randomized controlled trial by comparing the health data of nearly 300,000 adults over the age of 60, some of whom had high blood pressure and some of whom didn't, but all of whom were recently prescribed paracetamol by their physicians.
Compared to those patients who were prescribed painkillers without sodium, the authors found those who took daily paracetamol with sodium were slightly but significantly more at risk of heart attack, stroke, heart failure, and death a year later.
Without looking closer at individual patients, it's not clear how high salt intake might be impacting these outcomes, but numerous studies have shown a connection between sodium levels and cardiovascular disease among those with high blood pressure.
What's interesting about the findings of the current study, however, is that individuals with both high and normal blood pressure were at similar risk of heart issues when extra salt was added to their daily diets.
The actual risk only increased a percentage or so from those who take medication without sodium, but at a population level that's still significant.
Further tests will be needed to determine if this added dose of sodium ultimately led to higher blood pressure, thus impacting the health of the heart. Previous studies looking at how sodium-steeped medicine impacts blood pressure have produced inconclusive results.
In the meantime, researchers are warning doctors and patients to be aware that some medication can exceed sodium intake recommendations.
"People should pay attention not only to salt intake in their food but also not overlook hidden salt intake from the medication in their cabinet," says Chao Zeng from Xiangya Hospital, Central South University in China.
"Although the US Food and Drug Administration requires that all over-the-counter medications should label the sodium content, no warning has been issued about the potentially detrimental effect of sodium-containing paracetamol on the risks of hypertension, cardiovascular disease and death. Our results suggest re-visiting the safety profile of effervescent and soluble paracetamol."
Thankfully, there are some forms of dissolvable paracetamol available that are made without sodium, or only small amounts of it. These are great alternatives for those looking for the rapid effects of effervescent medicine without the possible downsides of long-term use.
In light of the new findings, an editorial, published alongside the current study, urges providers to ensure common painkillers are not causing undue harm to unsuspecting consumers.
"There is an immediate need for protection of consumers against these risks," write the authors of the editorial.
"The most plausible and effective strategy is likely to be the mandatory labeling of all medications containing significant quantities of sodium with a front-of-pack warning label. [..] Information programs that raise public and practitioner awareness of the hidden sodium in medications, and education about the need to avoid effervescent, dispersible, and soluble medicines in all but essential circumstances should also be considered."
The study was published in the European Heart Journal (link not yet live at time of publication).