Do salt tablets prevent cramps?

What actually causes exercise cramps?

A widely cited 2009 review in the British Journal of Sports Medicine looked at the two popular explanations. The dehydration and electrolyte-depletion theory rested mainly on anecdotes, case series totalling 18 cases and one small case-control study of 10 people. Four prospective cohort studies did not support it. The competing theory, altered neuromuscular control (a tiring muscle whose reflex signals go out of balance), has far better support from human cramp models and studies of cramping athletes.

In practice cramps cluster around going harder or longer than you trained for: quads on a long descent, calves late in a hilly marathon, hamstrings on the last climb of a cycle race.

Why do salt tablets seem to work?

Cramps usually ease when you slow down and stretch gently, which is also when people swallow a tablet. Oral salt takes a while to be absorbed, so it is unlikely to explain relief within seconds. The honest summary is that cramps have several causes and sodium is not shown to be the main one.

When does extra sodium genuinely help?

Sodium is the main mineral lost in sweat, and replacing it with fluid in long sessions helps hold plasma volume and fluid. The need is individual: sweat sodium ranges from about 10 to 90 mmol/L between athletes and sweat rates from 0.5 to over 2 L/h (Baker 2017). Heavy, salty sweaters (white salt marks on kit) in events over two hours in heat, such as a Durban summer long run or a Cape Epic stage, are the people most likely to benefit. Evidence level: moderate for sodium replacement, weak for cramp prevention.

What are the risks of salt tablets?

• Hyponatraemia is not prevented by tablets. It is caused mainly by overdrinking fluid beyond sweat losses, and sodium only slows it. See what is hyponatraemia.
• Concentrated salt can upset the stomach if taken without enough fluid.
• A large sodium load is unsuitable with high blood pressure, kidney or heart disease, or diuretic use.

What should you do instead?

1. Train for the distance and pace sensibly. This is the strongest cramp-prevention tool we have.
2. Fuel on schedule so fatigue does not set in early; see how to avoid hitting the wall.
3. Run a sweat test (weigh before and after an hour) and match fluid to thirst, as in how much water runners should drink.
4. If a cramp hits: ease off, stretch gently and keep moving.
5. If you are a salty sweater, use a proper electrolyte drink rather than loose salt. As of October 2026, Biogen Electrolyte sachets cost roughly R4.63 to R5.17 each at Dis-Chem and Lifestyle Electrolyte Fizzy tablets about R4.80 to R5.30 each; per-serving sodium is not published on the retailer pages we checked, so read the pack. Compare options on our best electrolytes in South Africa page.

When to see a doctor

See a doctor for frequent cramps at rest or at night, cramps with weakness or very dark urine after exertion, or if you take diuretics or blood pressure medication. For children and teenagers, water and normal food are enough for school sport. Pregnant women with leg cramps should ask their doctor or midwife before using salt or electrolyte products.

Products mentioned