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# Sodium hydrogen carbonate

Sodium bicarbonate: an alkali given IV to correct severe metabolic acidosis and to make the urine alkaline in some poisonings.

Updated 2026-11-01

- Class: [Electrolytes and rehydration solutions](https://durgical.com/en/pharmacology/classes/electrolytes-and-rehydration-solutions/)
- Target: Hydrogen ions: bicarbonate buffer of blood and urine (no receptor)
- ATC code: B05XA02
- WHO Model List of Essential Medicines

Also called: Sodium bicarbonate

## Mechanism of action

Bicarbonate combines with hydrogen ions to form carbonic acid, which breaks down into water and carbon dioxide that the lungs exhale. Blood pH rises. In the urine, bicarbonate makes the pH alkaline, which traps weak acids such as salicylates and some barbiturates in the urine (ion trapping) and speeds their elimination.

- Bicarbonate binds hydrogen ions in the blood
- Carbonic acid splits into water and CO₂, which is exhaled
- Blood pH rises
- Alkaline urine traps weak acids such as salicylates

## Pharmacokinetics

**Distribution**
Spreads through the extracellular fluid

**Elimination**
The CO₂ formed is exhaled; extra bicarbonate is excreted by the kidneys

**Onset and duration**
Acts quickly when given IV

## Indications

- Severe metabolic acidosis, for example from kidney disease, shock or uncontrolled diabetes [Chronic kidney disease →](https://durgical.com/en/conditions/chronic-kidney-disease/)
- Acidosis in circulatory shock or severe dehydration [Hypovolaemic shock →](https://durgical.com/en/conditions/hypovolaemic-shock/)
- Poisoning by salicylates, methanol or barbiturates (urine alkalinisation)
- Severe diarrhoea with bicarbonate loss

## Adverse effects

### Common

- Metabolic alkalosis with muscle twitching and irritability
- Fluid and sodium load (oedema)
- Low potassium
- Burning at the infusion site

### Serious (rare, important)

- Severe alkalosis with tetany
- Hypernatraemia and fluid overload in heart or kidney failure
- Tissue necrosis, ulceration or sloughing after extravasation
- Carpopedal spasm when low calcium is present

## Contraindications

- Chloride loss from vomiting or continuous gastric suction
- Diuretics that cause hypochloraemic alkalosis

## Key interactions

**Calcium-containing solutions**
Precipitate or haze in the same line

**Norepinephrine and dobutamine**
Physically incompatible in the same solution

**Salicylates**
Alkaline urine increases their excretion (used in poisoning)

## What is monitored

- Arterial blood gases and pH
- Sodium, potassium and calcium
- Fluid balance and signs of overload
- Infusion site

## Administration and safety

- Given IV; hypertonic solution is irritating: use a large, well-running vein and avoid extravasation, which causes necrosis.
- Incompatible with calcium solutions, norepinephrine and dobutamine: flush the line before and after.
- Correct low potassium and low calcium first or alongside, because rising pH lowers both.
- In newborns and children under two, rapid injection of hypertonic bicarbonate can cause hypernatraemia and possible intracranial haemorrhage; follow the paediatric protocol.

## Nursing care

- Check blood gases before and after doses; report a rising pH or bicarbonate.
- Watch for signs of alkalosis: twitching, tingling, cramps, slow breathing.
- Monitor potassium, which falls as pH rises.
- Check the IV site often; stop and report at the first sign of leakage.
- Watch for oedema and breathlessness in heart or kidney failure.

## Pregnancy and breastfeeding

Used when clearly needed; the sodium load and alkalosis are the concerns.

## Memory aid

Bicarbonate «buys back» hydrogen: it trades acid for CO₂ the lungs blow off, and in the urine it «traps» aspirin for the kidney to throw out.

## Test yourself

Think of the answer, then tap the question to see it.

## How does sodium bicarbonate help in salicylate poisoning?

It makes the urine alkaline; salicylate, a weak acid, ionises in the urine and is trapped there, so the kidney excretes more of it.

## Which IV drugs and solutions are incompatible with sodium bicarbonate?

Calcium-containing solutions (precipitate), and norepinephrine and dobutamine in the same solution.

## Why is sodium bicarbonate contraindicated with vomiting or gastric suction?

These cause chloride loss and metabolic alkalosis; adding bicarbonate worsens the alkalosis.

## Which electrolyte falls when bicarbonate raises the blood pH?

Potassium, which shifts into cells; ionised calcium also falls.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/pharmacology/sodium-hydrogen-carbonate/)

## Related drugs

- [Potassium chloride](https://durgical.com/en/pharmacology/potassium-chloride/)
- [Acetazolamide](https://durgical.com/en/pharmacology/acetazolamide/)

## Related conditions

- [Chronic kidney disease](https://durgical.com/en/conditions/chronic-kidney-disease/)
- [Hypovolaemic shock](https://durgical.com/en/conditions/hypovolaemic-shock/)

[← Back to the class: Electrolytes and rehydration solutions](https://durgical.com/en/pharmacology/classes/electrolytes-and-rehydration-solutions/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [DailyMed - SODIUM BICARBONATE- sodium bicarbonate injection, solution](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=5ae65432-04a1-4b6b-8536-2535064fc782) (DailyMed (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=B05XA02) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); [eEML - Electronic Essential Medicines List](https://list.essentialmeds.org/) (World Health Organization, 2025).

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