What drugs contain citric acid?

October 9, 2025 •

4 min read

Citric acid, a naturally occurring compound found in citrus fruits, is a cornerstone of pharmaceutical formulation due to its versatility and safety. It plays multiple critical roles as an inactive ingredient, and a wide variety of common medications contain citric acid.

Quick Summary

Citric acid is a ubiquitous inactive ingredient in pharmaceuticals, functioning as a preservative, pH regulator, flavoring agent, and effervescent compound. It is found in various medications, including antacids, urinary alkalinizers, and some oral and topical drugs.

Key Points

Excipient with Many Roles: Citric acid is used as a versatile excipient in pharmaceuticals, serving as a preservative, flavoring agent, buffer, and antioxidant.
Found in Effervescent Medications: It is a key ingredient in effervescent products like Alka-Seltzer, where it reacts with bicarbonate to produce fizzing that helps with rapid dissolution.
Enhances Palatability: In syrups and chewable tablets, citric acid masks bitter flavors, improving taste acceptance and patient compliance, especially among children.
Used in Urinary Alkalinizers: The salt form, sodium citrate, is used in medications such as Bicitra to make urine less acidic, helping to prevent certain types of kidney stones.
Concerns in Injectable Drugs: Citrate buffers in some injectable medications have been associated with injection site pain, leading some manufacturers to create citrate-free versions.
Potential for Enhanced Absorption: Citric acid can increase the absorption and bioavailability of certain drugs by altering cellular permeability.
Used in Laxatives and Contraceptives: Citrates are key components in osmotic laxative preparations and are an active ingredient in the non-hormonal contraceptive Phexxi.

Citric acid is a naturally occurring organic compound renowned in the pharmaceutical industry for its safety and functional versatility. It serves as a multi-functional excipient, which is a substance formulated alongside the active pharmaceutical ingredient (API) to improve stability, effectiveness, and palatability. By leveraging its chemical properties, manufacturers can produce a wide range of medications, from easy-to-swallow effervescent tablets to stable, long-lasting liquid solutions.

The Many Roles of Citric Acid in Medicine

Flavoring and Taste-Masking

One of the most common applications of citric acid is to improve the flavor of oral medications, particularly syrups, chewable tablets, and effervescent formulations. Its characteristic tangy or sour taste helps to mask the often unpleasant, bitter flavors of active ingredients. This is especially important for pediatric and geriatric populations, where patient compliance can be significantly improved by making the medication more palatable. Citric acid also stimulates salivary glands, which further helps with the taste and mouthfeel of a medication.

Preservative and Antioxidant

Citric acid acts as a natural preservative, inhibiting the growth of bacteria, molds, and fungi in pharmaceutical preparations. It also functions as a chelating agent, meaning it can bind to and sequester metal ions that might otherwise catalyze the degradation of the active ingredients through oxidation. This protective action enhances the overall stability and extends the shelf life of the medication.

Buffering and pH Control

Maintaining a specific pH is vital for the stability and bioavailability of many drugs. As a buffering agent, citric acid helps to regulate the acidity of formulations, keeping them within a desirable pH range. Without proper pH control, a drug's active ingredients could degrade over time or fail to be absorbed correctly by the body, rendering the medication ineffective.

Effervescent Formulations

In effervescent products, citric acid is combined with a carbonate or bicarbonate, such as sodium bicarbonate. When these ingredients are mixed with water, they react to produce carbon dioxide gas, creating the characteristic fizzing action. This process helps to rapidly dissolve and disperse the medication, allowing for faster absorption by the body, which is beneficial for patients with difficulty swallowing tablets.

Enhanced Drug Absorption

For some medications, citric acid can increase bioavailability by enhancing absorption. By sequestering calcium ions, it can increase the permeability of cell junctions, which promotes the transport of certain drug molecules across the intestinal wall. This is used in certain formulations to improve the effectiveness and speed of action of the drug.

Examples of Medications with Citric Acid

Citric acid and its salts, known as citrates, are found in a wide array of over-the-counter and prescription medications. Here is a list of some examples:

Alka-Seltzer products: Various formulations, including Alka-Seltzer Original and Alka-Seltzer Heartburn Relief, use citric acid and sodium bicarbonate for their effervescent properties.
Oral Solutions for Urinary Alkalinization: Medications like Bicitra, Oracit, and Polycitra contain citric acid along with sodium and/or potassium citrate to make urine less acidic, helping to prevent kidney stones and treat metabolic problems.
Osmotic Laxatives: Preparations for bowel cleansing before procedures like colonoscopy, such as Clenpiq and Prepopik, utilize citric acid in combination with other ingredients to produce magnesium citrate.
Certain Oral and Topical Medications: Citric acid is used as an excipient in some extended-release formulations like Bupropion XL, chewable tablets like Dramamine for Kids, and topical treatments.
Contraceptives: The non-hormonal contraceptive agent Phexxi lists citric acid as an active ingredient.

Citric Acid vs. Citrates: What's the Difference?


Feature	Citric Acid	Citrates
Chemical State	Anhydrous (crystal) or monohydrate	Salt derivatives (e.g., sodium citrate, potassium citrate, magnesium citrate)
Acidity/pH	Lowers pH of solution; acidic	Buffering agent; adjusts pH to be more neutral or alkaline
Primary Role in Formulation	Taste-masker, preservative, antioxidant, effervescent agent	Urinary alkalinizer, anticoagulant (binds calcium), osmotic laxative
Examples in Medicine	Alka-Seltzer (reacts with bicarbonate), some chewable tablets	Bicitra, Polycitra (urinary alkalinizers), blood storage solutions (anticoagulant)

Considerations and Concerns

While citric acid is generally considered safe, there are some medical considerations. In individuals with chronic kidney dysfunction, the chelating properties of citrates can increase the absorption of ions like aluminum from other medications (e.g., aluminum hydroxide antacids), potentially leading to toxicity. Furthermore, the acidic nature of citric acid in injectable formulations can contribute to injection site pain by activating specific acid-sensing ion channels. For this reason, some injectable drugs, like adalimumab (Humira), have been reformulated to be citrate-free to improve patient comfort and compliance.

Conclusion

Citric acid and its citrate salts are far from inert fillers in pharmaceuticals; they are strategic ingredients with multiple critical functions. From making medicine taste better to ensuring its stability and controlled release, its versatile properties contribute significantly to the safety, effectiveness, and patient experience of a vast range of products. As the pharmaceutical industry continues to innovate, citric acid remains a fundamental component, with ongoing research even exploring its use in biomaterials for regenerative medicine. Understanding its diverse applications provides valuable insight into the science behind drug formulation.

For more in-depth information on the functions of citric acid in pharmaceuticals, you can review the extensive research available at PMC.

Frequently Asked Questions

Citric acid is used in medications for several reasons, including masking unpleasant tastes, preserving ingredients from oxidation and microbial growth, regulating pH levels, and creating the effervescence in fizzing tablets.

Yes, citric acid is a common ingredient in many over-the-counter products. Examples include effervescent antacids like Alka-Seltzer and certain chewable children's medications.

For most people, the citric acid in medications is safe and doesn't cause side effects. However, for individuals with chronic kidney dysfunction, the citrate can increase the absorption of aluminum from other medicines, which may lead to toxicity. Also, some people report injection site pain with citrate-buffered injectable drugs.

Citric acid is the acidic form, while citrates are the salt derivatives (like sodium citrate). Citric acid is generally used as a flavoring and preservative, while citrates act as buffers, alkalinizers, or anticoagulants depending on the specific formulation.

While most commonly an inactive ingredient, citric acid is listed as an active ingredient in some products. For instance, the non-hormonal contraceptive Phexxi and certain urinary alkalinizer solutions contain citric acid as an active component.

As an antioxidant, citric acid works by chelating, or binding, with metal ions that can trigger oxidation reactions. By sequestering these metals, it prevents the degradation of the active ingredients, thereby extending the medication's shelf life.

Yes, some medications have been specifically reformulated to be citrate-free. A notable example is a version of adalimumab (Humira), which was changed to remove the citrate buffer to reduce injection site pain and improve patient comfort.