Sodium Benzoate Side Effects

Sodium benzoate is a chemical used as a preservative in for several types of food, including margarine, soft drinks, pickles, jelly and jam. Although sodium benzoate is usually safe, it may cause mild side effects in certain individuals. Sodium benzoate is also commonly mixed together with another chemical, sodium phenylacetate, and used to treat a condition known as hyperammonemia, which is characterized by excess levels of ammonia in the blood. The mixture of sodium benzoate and sodium phenylacetate may cause more side effects than sodium benzoate alone.

When used alone as a preservative, sodium benzoate rarely causes side effects, even when consumed in large doses of up to 50 g, reports Oregon State University. In certain individuals, nausea and vomiting may occur. In rare cases, sodium benzoate can irritate existing stomach ulcers and cause mild hyperventilation, possibly leading to dizziness and lightheadedness, according to the Hazardous Substances Data Bank of the National Library of Medicine.

The mixture of sodium benzoate and sodium phenylacetate, which is sold under several brand names, such as Ucephan and Ammonul, can cause several side effects. The more common side effects include headache, nausea, vomiting, dry mouth, appetite loss and mood changes, reports MayoClinic.com. Confusion, muscle pain, fatigue, difficulty moving, shortness of breath, seizures and convulsions are also possible.

In rare cases, taking sodium benzoate and sodium phenylacetate may result in more severe side effects, including severe bruising, blood in the stools or urine, vomiting blood, difficulty breathing or changes in breathing patterns, drowsiness or unconsciousness. Additional rare side effects include muscle cramps, tremors, rash, restlessness and a feeling of tightness in the chest.

Additional severe side effects may result from the combination of sodium benzoate and sodium phenylacetate, including severe headache, fainting, blurred vision, chest pains, slowed heartbeat, unresponsiveness and slurred speech. Several unusual side effects are also possible, including a blue coloring of the lips, skin or fingernails; changes in the perception of colors, particularly yellow and blue; or a bulging soft spot developing on the head of an infant given the medication.