Heartburn and Baking Soda: An Old Remedy With a Real Sodium Problem

Sodium bicarbonate is a legitimate antacid. It appears in over-the-counter antacid monographs, it has been used for this purpose for well over a century, and it works within minutes. It is also the use with the largest gap between "generally fine" and "occasionally very bad", so this article spends most of its length on the second part.

How it works

Stomach acid is hydrochloric acid. Bicarbonate neutralises it directly, producing salt, water and carbon dioxide. Relief is fast — usually a few minutes — which is exactly why it caught on. The carbon dioxide is also why it often produces a substantial burp, and why it can briefly make reflux feel worse before it feels better.

The sodium, again

Half a teaspoon delivers roughly 600 mg of sodium. Most health authorities put the daily limit somewhere around 2,000–2,300 mg. Take it three times in a day and you have spent most of your allowance on indigestion. For anyone with high blood pressure, heart failure, or kidney disease, that is not a footnote — it is the reason this is contraindicated for them.

The specific harms, which are documented

• Gastric rupture. There is a small but real medical literature of stomach rupture after large doses of baking soda taken on a full stomach — the gas has nowhere to go. Rare, catastrophic, and the reason the standard advice is never to take it after a large meal.
• Metabolic alkalosis. Repeated or large doses can push blood pH up, causing confusion, muscle twitching, nausea and irregular heart rhythm. It is the classic complication of people self-treating daily for weeks.
• Milk-alkali syndrome. Bicarbonate plus large amounts of calcium — supplements or dairy — can produce high blood calcium and kidney injury.
• Fluid retention and raised blood pressure from the sodium load, most consequential in exactly the people most likely to reach for a cheap home remedy.
• Poisoning in children. Small bodies, adult doses. Poison control centres field these calls. Keep it out of reach and never give it to a child without medical advice.

Drug interactions worth knowing

Raising stomach pH changes how some medicines dissolve and absorb, and raising urine pH changes how some are excreted. The list is long and includes several common drugs — certain antibiotics, iron supplements, some antifungals, aspirin, lithium, and enteric-coated tablets, whose coating is designed around stomach acidity. If you take anything regularly, ask a pharmacist before making bicarbonate a habit. It is free advice and they will not mind.

If you are going to use it once

• Half a teaspoon (about 2.5 g) in a full glass of water — at least 200 ml.
• Not within two hours of a large meal, and not lying down.
• Not more than once or twice in a day, and not for more than a couple of days.
• Not at all if you are pregnant, under 18, over 60, or on any of the medicines above, without asking first.
• Do not take the "half teaspoon in water" advice from a source that has not mentioned any of the above.

When heartburn is not heartburn

This is the part that matters most. Chest discomfort has a differential diagnosis that includes things a kitchen remedy cannot touch — and reaching for a home antacid has, more than once, delayed someone getting to a hospital.

The honest recommendation

For occasional indigestion, a commercial antacid is a better instrument than the box in your cupboard: a measured dose, a lower sodium load, and a leaflet listing the interactions. Baking soda is a reasonable substitute at 11pm when you have none in the house. It is a poor routine, and persistent heartburn is a reason to see someone rather than to buy a bigger box.