Does Tolterodine Contain Red Dye 40?
No, tolterodine does not contain Red Dye 40 (also known as Allura Red AC or FD&C Red No. 40). According to the FDA drug label, the 1 mg tolterodine tartrate tablets contain iron oxide yellow and iron oxide red as colorants, not Red Dye 40 1.
Specific Inactive Ingredients in Tolterodine
The complete list of inactive ingredients in tolterodine tartrate tablets includes 1:
- Colloidal silicon dioxide
- Dibasic calcium phosphate dihydrate
- Hypromellose
- Magnesium stearate
- Microcrystalline cellulose
- Purified stearic acid
- Sodium starch glycolate
- Titanium dioxide
The 1 mg tablet specifically contains iron oxide yellow and iron oxide red as additional colorants 1.
Important Distinction: Iron Oxide Red vs. Red Dye 40
Iron oxide red is a mineral-based pigment, while Red Dye 40 is a synthetic azo dye derived from petroleum. These are completely different substances with different chemical structures and different allergy profiles. Patients with documented allergies to synthetic azo dyes like Red Dye 40 can safely take tolterodine, as it does not contain this ingredient 1.
Clinical Relevance
- If a patient reports an allergy to "red dye," clarify whether they mean synthetic azo dyes (like Red Dye 40) or iron oxide pigments, as these are distinct substances 1
- The 2 mg tolterodine tablet does not contain any iron oxide colorants and would be appropriate for patients with iron oxide sensitivities 1
- Both the 1 mg and 2 mg formulations are free of Red Dye 40 1