Salt tablets are concentrated doses of sodium chloride, typically taken to replace sodium lost through heavy sweating, to treat low blood sodium levels, or to manage conditions that cause excessive salt loss. They come in standard tablets (usually 1 gram each) and modified-release versions designed to dissolve more slowly in the stomach. While most people get plenty of sodium from food, certain situations create a deficit that diet alone can’t keep up with.
How Sodium Works in Your Body
Most of the sodium in your body sits in your blood and the fluid surrounding your cells. Its primary job is maintaining fluid balance: sodium essentially controls how much water your body holds onto and where that water goes. When sodium levels are stable, blood volume stays normal, blood pressure stays regulated, and your muscles and nerves fire correctly.
Your kidneys are the main control system. When sodium runs too high, they dump more into your urine. When it drops too low, the kidneys trigger hormones that slow down urine production and hold onto whatever sodium is available. This system works well under normal conditions, but it can be overwhelmed when sodium leaves the body faster than the kidneys can compensate, which is where salt tablets come in.
Replacing Sodium During Prolonged Exercise
This is the most common reason healthy people use salt tablets. During exercise, sweat carries sodium out of the body at an average concentration of about 1 gram per liter. Sweat rates vary enormously, from as little as 0.3 liters per hour to over 2.4 liters per hour, depending on the person, the intensity, and the heat. A heavy sweater exercising in hot weather for several hours can lose significant amounts of sodium that water alone won’t replace.
The American College of Sports Medicine recommends 300 to 600 milligrams of sodium per hour during prolonged exercise, which works out to roughly 1.7 to 2.9 grams of salt. Sodium replacement is generally recommended when exercise lasts longer than two hours, when conditions are hot, or when total sodium loss exceeds 3 to 4 grams. At those levels, sodium helps maintain blood volume, keeps your thirst drive working properly, reduces urine output so you retain more fluid, and supports the electrical signals that keep muscles contracting.
One important caveat: salt tablets during a race can slow the drop in blood sodium, but they cannot prevent a dangerous condition called exercise-associated hyponatremia if you’re simultaneously drinking excessive amounts of water. Overhydration dilutes your blood sodium regardless of how many tablets you take.
Treating Low Blood Sodium in Medical Settings
Low blood sodium (hyponatremia) is a real clinical problem, particularly in older adults. It can cause confusion, fatigue, nausea, and in severe cases, seizures. One common cause is a condition where the body produces too much of a hormone that tells the kidneys to retain water, diluting the sodium in your blood.
In hospitals, modified-release salt tablets are sometimes prescribed alongside fluid restriction to gradually bring sodium levels back up. In published case reports, doses of 2.4 grams twice daily improved blood sodium from dangerously low levels to near-normal within three to five days. These tablets are typically used temporarily while doctors work out what’s causing the problem, and they’re monitored closely because correcting sodium too quickly carries its own risks.
Cystic Fibrosis and Chronic Salt Loss
People with cystic fibrosis lose unusually high amounts of sodium and chloride in their sweat due to the underlying biology of the disease. This makes them more vulnerable to salt depletion, especially during exercise, hot weather, or illness. There’s no single standard dose for salt replacement in cystic fibrosis. It depends on activity level, weather, symptoms, and how much sodium is already coming from food. Some people use salt tablets directly, while others add extra salt to sports drinks or meals.
Side Effects of Salt Tablets
Concentrated salt hitting the stomach can cause nausea, vomiting, dizziness, headache, and fatigue. Modified-release tablets were developed partly to reduce this stomach irritation by dissolving more gradually. Taking salt tablets with plenty of water also helps, both for absorption and to buffer the effect on your stomach lining.
The more serious concern is taking salt tablets when you don’t actually need them. Extra sodium raises blood pressure. In one controlled trial, participants taking salt tablets had systolic blood pressure roughly 4 mmHg higher than those on placebo, along with early signs of kidney stress. High sodium intake is also linked to faster progression of chronic kidney disease, with one study finding a 54% increased risk of worsening kidney function among those with the highest sodium excretion. For anyone with high blood pressure, kidney disease, or heart failure, salt tablets can make things meaningfully worse.
Who Actually Needs Them
Salt tablets fill a narrow but important gap. They’re genuinely useful for endurance athletes training or competing for more than two hours in the heat, for people with medically confirmed low sodium levels, and for those with conditions like cystic fibrosis that cause chronic salt wasting. Outside those situations, most people already consume more sodium than they need from food. A typical Western diet provides 3,000 to 5,000 milligrams of sodium per day, well above the recommended limit of 2,300 milligrams.
If you’re a recreational exerciser working out for under an hour in moderate conditions, a normal diet almost certainly covers your sodium needs. Salt tablets become relevant when losses are high, sustained, and difficult to replace through regular eating, which is a real scenario for some people but not most.