Citric Acid Drug Interactions, Uses, Effectiveness, Safety & More

Citric acid is a weak organic acid that gives citrus fruits like lemons, limes, and oranges their sour taste. It occurs naturally in many fruits and is also a normal part of the body's energy-making process, called the citric acid cycle.

Most citric acid sold today is not squeezed from fruit. Instead, it is made on a large scale by fermenting sugars with a mold called Aspergillus niger. This produces a cheap, food-grade white powder used around the world.

People most often run into citric acid as a food and drink ingredient, where it adds tartness, balances flavor, and helps keep products fresh. It also appears in supplements, effervescent (fizzy) tablets, and some over-the-counter health products. Related forms called citrate salts (such as potassium citrate and sodium citrate) are used in medicine.

Citric acid is an acid, so it lowers the pH (raises the acidity) of whatever it is added to. This is what makes it useful for flavor, for preserving foods by slowing the growth of microbes, and for keeping certain ingredients stable.

In the body, citric acid is part of the citric acid cycle (also called the Krebs cycle), a key set of chemical reactions cells use to turn food into energy. The citric acid you eat is normally broken down and used like other nutrients.

When taken as a citrate salt, the citrate is processed in the body and can make the urine more alkaline (less acidic). This change in urine chemistry is what helps certain kidney stones from forming. Much of the detail behind these effects comes from chemistry and clinical use of citrate, rather than from studies of plain citric acid powder.

For most people, the citric acid found in foods, drinks, and ordinary supplements is safe. Regulators consider it generally recognized as safe at the levels normally used.

Concentrated citric acid is a strong acid and can irritate the eyes, skin, mouth, throat, and stomach if used in large amounts or in pure form. People with acid reflux, ulcers, mouth sores, or sensitive teeth may notice more discomfort. Over time, frequent acidic drinks can contribute to tooth enamel erosion.

Medicinal citrate products (potassium or sodium citrate) carry more cautions. People with kidney disease, heart failure, or those who must limit potassium or sodium should only use these under medical supervision.

Pregnancy and breastfeeding: the small amounts in food are considered fine. However, there is not enough information on concentrated citric acid or high-dose citrate supplements during pregnancy and breastfeeding, so it is safest to check with your doctor or pharmacist before using them.

In food amounts, citric acid rarely causes problems. When side effects do occur, they are usually from concentrated forms or large amounts and may include:

• Mouth or throat irritation and a sour or burning feeling
• Stomach upset, heartburn, or worsening of reflux
• Tooth enamel wearing down with frequent acidic intake
• Skin or eye irritation from direct contact with the powder or liquid

Citrate salt supplements can cause stomach upset, nausea, or diarrhea, and high doses may affect potassium or sodium levels in people who are sensitive. Serious reactions are uncommon, but stop use and seek care if you have severe pain, trouble breathing, or signs of an allergic reaction.

There is no standard supplement dose of plain citric acid, because it is mainly used as a food ingredient rather than a treatment. Amounts used in foods and drinks are small and considered safe.

For medicinal citrate products (such as potassium citrate or sodium citrate used for kidney stones or urine alkalinization), dosing is individualized and should be set by a doctor, often based on lab tests. Do not try to self-treat kidney or urinary conditions with citric acid powder.

Always follow the directions on the product label and check with a pharmacist or doctor before using citric acid or citrate supplements for a health purpose, especially if you have kidney, heart, or stomach problems.