Effervescent medications (painkillers, vitamins etc) contain high quantities of sodium in the form of sodium carbonate. It is recommended by many health organizations that sodium should be restricted from diet since it elevated blood pressure and increases the risk of heart attack and stroke. Despite those recommendations for diet, no recommendations have been published until now regarding the sodium content of medications.
A study which was published in British Medical Journal on 26 November 2013, found that people who used effervescent medications had a higher risk to suffer from hypertension, heart attack and stroke.
Of course, effervescent medications cannot be completely restricted since they are extremely useful for people who cannot swallow pills or when we need faster onset of action. On the other hand, we should use them with caution, especially in cases where there is already elevated blood pressure or high risk of stroke and heart attack.