What is tartrazine?

Tartrazine: Food Dye with Potential Allergic Implications

Tartrazine (FD&C Yellow No. 5) is an artificial azo dye commonly used in foods, medications, and cosmetics that can cause allergic reactions such as urticaria and asthma in sensitive individuals, particularly those with aspirin sensitivity. 1

Chemical Properties and Usage

Tartrazine is a vibrant yellow synthetic food coloring agent that belongs to the azo dye class. It is widely used as an additive in:

• Processed foods and beverages
• Medications (particularly in oral formulations)
• Cosmetics

When used in oral food challenges for allergy testing, tartrazine is typically administered at doses of 25 mg and 50 mg at 3-hour intervals, following a placebo 2.

Metabolism and Toxicology

When consumed, tartrazine undergoes metabolism in the gastrointestinal tract:

• Gut bacteria can reduce tartrazine to metabolites including sulfanilic acid and 4-amino-3-carboxy-5-hydroxy-1-(4-sulfophenyl)pyrazole (SCAP) 3
• These metabolites can undergo further oxidation when exposed to air, forming compounds like purpurazoic acid (PPA) 3
• Some metabolites have demonstrated moderate toxicity to human cells in laboratory studies 3

Adverse Reactions

Tartrazine sensitivity manifests primarily as:

• Urticaria (hives)
• Asthma exacerbations
• Less commonly: vasculitis, purpura, and contact dermatitis 1

Cross-Sensitivity

An important clinical consideration is the cross-reactivity between tartrazine and other substances:

• Patients with aspirin sensitivity may also react to tartrazine
• Cross-sensitivity with non-steroidal anti-inflammatory drugs (NSAIDs) has been reported 1

Prevalence and Risk Assessment

The prevalence of tartrazine intolerance is relatively low:

• Estimated to affect less than 0.12% of the general population 4
• More common in individuals with recurrent urticaria or asthma 4
• From a toxicological perspective, normal consumption levels are generally considered safe for most people 4

Clinical Management

For patients with suspected tartrazine sensitivity:

1. Avoidance is the primary management strategy - patients should avoid foods, medications, and cosmetics containing tartrazine 1

2. Careful label reading - educate patients about the importance of checking ingredient lists for "tartrazine" or "FD&C Yellow No. 5"

3. Challenge testing - when diagnosis is uncertain, double-blind placebo-controlled challenges can be conducted under medical supervision 5

4. Medication considerations - when prescribing medications, be aware that tartrazine is present in many oral formulations

Special Considerations for Allergy Testing

When performing allergy testing:

• Antihistamines, including first-generation ones like diphenhydramine, should be discontinued 7-10 days before oral food challenges or allergy testing 6
• This ensures accurate results when testing for tartrazine sensitivity

Regulatory Status

Due to concerns about potential adverse reactions, regulatory agencies require:

• Clear labeling of tartrazine on food packages and medication inserts
• This allows sensitive individuals to identify and avoid products containing the dye 1

While tartrazine is generally recognized as safe for most consumers at approved levels, healthcare providers should remain vigilant about potential sensitivity reactions, particularly in patients with a history of asthma, chronic urticaria, or NSAID sensitivity.