Citric Acid

Medically Reviewed by Carmelita Swiner, MD on August 02, 2022
4 min read

Citric acid is a weak acid that is found naturally in all citrus fruits. If you’ve ever sunk your teeth into a lemon, you've tasted citric acid. Manufacturers add a man-made version of it to processed foods. Medicines with citric acid in them treat health issues like kidney stones.

It's not just sour citrus fruits that have citric acid. All plants and animals have small traces of it. Many packaged food and nonfood items, like cosmetics and cleaning products, also contain citric acid, but a manufactured version, not the type that you find in nature.

Natural sources of citric acid

Foods that are high in natural citric acid are citrus fruits, especially the juice of lemons and limes. Other fruits and vegetables also contain some natural citric acid.

These foods have the highest amounts of naturally occurring citric acid:

  • Lemons
  • Limes
  • Oranges
  • Grapefruits
  • Berries

Artificial sources and uses of citric acid

The citric acid that’s added to food and drinks, medications, personal care products, and cleaning products is artificial.

This type of citric acid is used in:

  • The food industry. Citric acid is often added to packaged food and drinks. It helps keep canned and jarred foods fresh over long periods of time. It can prevent some kinds of fresh-cut produce, like sliced apples, from turning brown. Citric acid can also help thicken foods or give them a slightly sour flavor. That's why you might see citric acid listed as an ingredient in some ice creams, sorbets, or sodas.
  • Alcohol. Citric acid can balance out the acid in a food or drink. Winemakers sometimes add it to their products to improve the taste.
  • Medicines. Some creams include citric acid to help clear up skin infections. Other citric acid drugs that you take by mouth can lower the amount of acid in your urine. This can help prevent kidney stones. You might also take citric acid for metabolic acidosis, a buildup of acid inside your body.
  • Supplements. Some people take calcium citrate supplements, which can help prevent kidney stones.
  • Personal care products. When manufacturers mix citric acid with other ingredients, they can form a compound called "alpha hydroxy acid" that helps smooth your skin. It's also in some cosmetics and toiletries -- like lipstick, hair spray, and deodorant -- to help them last longer.
  • Household cleaners. Because citric acid can eat away at hard water buildup, you'll often see it in dishwasher detergent. Other household cleaners also include it as an ingredient since it can help remove stains and odors.
  • Disinfectants. Since citric acid kills some types of bacteria and viruses, you'll find it in insect sprays, products that kill fungus or algae, hand sanitizer, and even some tissues you use to blow your nose.
  • Environmental cleanup products. Citric acid can safely remove toxins from polluted soil and even clean up nuclear waste.

There are many reasons to add citric acid to food, medicine, or other products. It can:

  • Preserve food. It is used to keep food fresh for longer periods. In some cases, it may prevent foodborne botulism, an illness that can be caused by home-canned foods that are low in acid.
  • Preserve personal care products. It may keep cosmetics and other products fresh for longer.
  • Have protective effects in the body. Citric acid used in medicine can kill bacteria and lower the acid in urine.
  • Remove tough stains. For this reason, it’s added to some cleaning products.

The FDA says citric acid is "generally recognized as safe" in food and skin products. Still, some experts think that more research is needed.

Citric acid may cause:

Skin irritation. When it touches your skin for long periods of time, it can cause stinging, swelling, or hives.

Eye pain. It will burn if it gets in your eyes. If this happens, flush them well with water for several minutes. If you wear contact lenses, take them out as soon as you can.

Tooth problems. Drinks and candies that contain citric acid can wear away the enamel (the outer layer) of your teeth. This can make your teeth more sensitive, turn them yellow, and make it more likely you'll get cavities.

Upset stomach. If you take a medicine with citric acid by mouth, you can have side effects like nausea or vomiting.

Sometimes, drugs with citric acid can cause severe side effects, such as:

  • Confusion
  • Lightheadedness
  • Chest pain
  • Fast heartbeat
  • Pain
  • Tingling or numbness in your hands or feet
  • Fatigue

If you notice any of these symptoms, contact your doctor right away.