Is Indigo Carmine Safe to Consume? An In-Depth Look

December 24, 2025 •

4 min read

According to the European Food Safety Authority (EFSA), purified indigo carmine (E132) is considered safe for consumption within the established Acceptable Daily Intake (ADI) of 5 mg/kg body weight. This synthetic blue food dye is widely used, yet its safety is a frequent consumer concern.

Quick Summary

This article examines indigo carmine's regulatory status, potential health risks, and common uses as a food and pharmaceutical dye. It reviews how major food safety authorities assess its safety.

Key Points

Regulatory Approval: Major food safety authorities like the EFSA and FDA have approved indigo carmine (E132) for use as a food additive within specified limits, based on extensive safety reviews.
Acceptable Daily Intake (ADI): The EFSA confirmed the ADI for indigo carmine at 5 mg per kg of body weight per day, concluding there is no safety concern at the approved levels.
Purity is Key: Safety assessments depend heavily on the dye's purity. Modern manufacturing processes limit impurities that historically raised minor concerns.
Potential Side Effects: Reported side effects include rare allergic reactions and potential gastrointestinal irritation at high doses or with less pure forms.
Consumption is Not High-Risk: The amount of indigo carmine in food is typically low and well below the ADI for the general population.
Found in Processed Foods: Indigo carmine is a common synthetic blue dye found in a variety of processed foods, including candies, desserts, and beverages.
Medical vs. Food Use: The injected form used in medical procedures has different safety considerations and potential cardiovascular side effects that are not relevant to food consumption.

What is Indigo Carmine (E132)?

Indigo carmine, also known as indigotine, FD&C Blue No. 2, or E132 in Europe, is a synthetic blue food dye derived from indigo. Unlike natural indigo, the sulfonation process makes indigo carmine water-soluble, which is essential for its application in food production. It is used to achieve a vibrant blue color in various products and can also be combined with other dyes, such as yellow, to create different shades of green. Beyond its role in food, indigo carmine also has medical applications as a diagnostic and staining agent in surgical procedures.

Regulation and Safety Assessments

Major food safety organizations worldwide have evaluated indigo carmine to determine its safety for human consumption. Their findings and regulations dictate how the dye can be used in food products.

European Food Safety Authority (EFSA): EFSA re-evaluated indigo carmine (E132) in 2023, confirming its Acceptable Daily Intake (ADI) at 5 mg/kg body weight per day. This was based on a review of toxicological data, including a 56-day dietary study that addressed concerns from an older study regarding adverse effects on the testes in mice. The latest assessment concluded there was no safety concern for its use within approved limits and with updated purity specifications.
U.S. Food and Drug Administration (FDA): The FDA regulates FD&C Blue No. 2 as a color additive and permits its use under current Good Manufacturing Practices (cGMPs) in specific food products. While the FDA has permitted its use for food coloring, it is important to distinguish this from the injectable form of indigo carmine (indigotindisulfonate sodium), which received recent approval as a diagnostic dye but has different safety considerations.

Potential Health Risks and Side Effects

Despite its approval, indigo carmine is not without potential risks, especially for sensitive individuals or when impurities are present. The primary health concerns are generally associated with high exposure or contaminants.

Allergic Reactions: In rare cases, individuals may experience allergic or allergy-like reactions to indigotine, including hives (urticaria). A case report cited in medical literature involved a patient reacting to indigotine in thyroid medication, though food-related effects are less common.
Gastrointestinal Issues: Ingestion of the dye, particularly at higher concentrations, has been linked to gastrointestinal irritation, potentially causing symptoms like nausea, vomiting, and diarrhea.
Cardiovascular Effects (Medical Use): The injectable form of indigo carmine, used in medical procedures, can cause a transient elevation in blood pressure and reflex bradycardia (slowed heart rate). However, this is specific to intravenous administration and not typically a concern for food consumption.
Purity Concerns: Past studies have raised concerns regarding trace amounts of unsulfonated aromatic amines, which could have genotoxic potential. However, modern manufacturing processes and updated regulatory specifications aim to control these impurities to levels that are not considered a health concern.

Comparison of Indigo Carmine with Other Blue Dyes

To provide context, here is a comparison of indigo carmine with other blue food colorants, highlighting key differences in their source, use, and stability.


Feature	Indigo Carmine (E132 / FD&C Blue No. 2)	Brilliant Blue FCF (E133 / FD&C Blue No. 1)	Spirulina Extract (Natural Blue)
Source	Synthetic, sulfonated indigo	Synthetic, coal tar derivative	Derived from blue-green algae
Stability	Moderate heat stability, poor light and oxidation stability.	Very high light, heat, and acid stability.	Poor stability, especially in acidic conditions.
Regulatory Status	Approved for consumption by FDA and EFSA, with specified limits.	Widely approved for use in food and cosmetics.	Approved in many regions as a natural colorant.
Potential Issues	Rare allergic reactions, potential GI issues with high doses or contaminants.	Possible allergic reactions, controversial links to hyperactivity in children (EFSA did not confirm).	Generally considered safe, but natural color may be less vibrant.
Common Uses	Ice cream, candy, baked goods, medications.	Beverages, desserts, cereals, baked goods.	Confectionery, dairy products, ice cream.

What Foods Contain Indigo Carmine?

Indigo carmine is commonly used across a wide range of processed foods and beverages to create a blue or green color. Its use and maximum permitted levels (MPLs) vary by region, though typical examples include:

Confectionery: Hard and soft candies, sweets, and nougats.
Desserts: Puddings, ice cream, jellies, and other dessert products.
Beverages: Water-based flavored drinks, some spirituous beverages.
Baked Goods: Fine bakery wares, icings, and decorations.
Pharmaceuticals: Outer coating of some tablets and capsules.

How to Limit Indigo Carmine Intake

For consumers concerned about synthetic food dyes, limiting intake of indigo carmine and other artificial colorants is a matter of making informed dietary choices.

Read Ingredient Labels: Check the ingredient list for "indigo carmine," "indigotine," "E132," or "FD&C Blue No. 2."
Choose Natural Alternatives: Opt for products that use natural colorants, such as spirulina extract, instead of synthetic dyes.
Prepare Food at Home: Cooking and baking from scratch allows for complete control over the ingredients used, avoiding unwanted additives.
Buy Unprocessed Foods: Focus on whole, unprocessed foods like fresh fruits, vegetables, and whole grains, which naturally do not contain synthetic dyes.

Conclusion

Based on the extensive scientific evaluations by global food safety authorities like EFSA, indigo carmine (E132) is considered safe for human consumption when used within approved maximum levels and with high purity. The established Acceptable Daily Intake (ADI) accounts for potential risks associated with historical impurities. While potential for rare allergic reactions exists, the dye is generally safe for most of the population in the small quantities used in food. Concerns about side effects and toxicity are most often associated with high-dose medical applications or historical studies involving less-pure forms of the dye. Consumers who prefer to avoid synthetic additives can easily identify and limit their intake by checking product labels for the E132 code or FD&C Blue No. 2. EFSA Journal - Re-evaluation of Indigo Carmine

Frequently Asked Questions

Indigo carmine (E132) is a synthetic, water-soluble food dye. While its base compound is related to natural indigo, the final product is chemically synthesized for use as a food additive.

There is no conclusive evidence that indigo carmine alone causes hyperactivity. While some studies have explored links between synthetic dyes and behavioral changes, scientific bodies regulate E132 for broader safety, not specifically for hyperactivity concerns like some other colorants.

Indigo carmine (E132) is a synthetic blue dye, whereas carmine (E120) is a natural red dye derived from cochineal insects. They are entirely different substances with distinct chemical compositions and potential side effects.

Indigo carmine can be found in a range of processed foods and beverages, including ice cream, flavored milk products, desserts, confectionery, and some pharmaceutical coatings.

Yes, the purity of indigo carmine is crucial for its safety. The acceptable daily intake (ADI) is established for highly pure versions of the dye, with regulatory specifications controlling levels of potential toxic impurities.

To avoid indigo carmine, you can check product labels for E132 or FD&C Blue No. 2. Opting for products made with natural colorants or focusing on whole, unprocessed foods can also help reduce your intake.

Though rare, allergic reactions to indigotine have been reported. If you have a known sensitivity to dyes, it's wise to avoid products containing indigo carmine. A medical consultation is recommended for those with severe allergies.

Yes, the safety profiles differ based on application. While the food additive is approved for ingestion in low doses, the medical form, an injectable diagnostic dye, can cause cardiovascular side effects due to its intravenous administration.