D&C Red No. 33
D&C Red No. 33 suppliers and sourcing guide
D&C Red No. 33 is a water-soluble red azo dye, principally the disodium salt of 5-amino-4-hydroxy-3-(phenylazo)-2,7-naphthalenedisulfonic acid. It is made by diazotizing aniline and coupling it with an aminonaphthol disulfonic acid, then isolating the sodium salt. It is a certified color for drugs and cosmetics, not food, used in mouthwashes, toothpastes, lip products, soaps and some tablets.
- Category
- Colors
- Also known as
- Acid Red 33 · CI 17200 · CAS 3567-66-6
- Facts checked
- November 2026
Forms and grades of d&c red no. 33
Suppliers sell different products under the same name. Specify the one you need.
Straight color powder
The water-soluble sodium salt at a stated total color, dissolved before use in aqueous products.
Aluminum lake
The dye laked onto alumina for lip products, powders and tablet coatings where bleeding must be avoided.
Liquid solution
Aqueous or glycol solutions at a stated dye percentage for mouthwash and liquid soap plants.
Pre-mixed shades
Blends with other certified colors, each from a certified lot.
What to check on the COA
Compare each result with your own specification when the lot arrives.
- FDA certification lot number
- Every batch of D&C Red No. 33 must carry an FDA certification lot number; check that the number on the COA, the certificate and the container match.
- Total color
- Pure dye content by spectrophotometry or titration against the 21 CFR part 74 minimum (not less than 82 percent); it sets how much color each kilogram delivers.
- Volatile matter and salts
- Volatile matter at 135 °C plus chlorides and sulfates (as sodium salts), which make up most of the non-dye portion of a straight color.
- Aromatic amines and intermediates
- Aniline, 4-aminoazobenzene, 4-aminobiphenyl, azobenzene, benzidine and 1,3-diphenyltriazene by HPLC or GC, against the ppm and ppb limits in 21 CFR 74.1333.
- Heavy metals
- Lead, arsenic and mercury by ICP-MS or AAS, reported against the limits in the color additive regulation and the supplier specification.
- Shade and strength vs. standard
- Hue and color strength compared with the supplier's retained standard, by drawdown or spectrophotometer, to catch shade drift between lots.
Storage, lots and expiry
Storage and shelf life
Store in the original sealed containers in a cool, dry place away from light and heat; powders cake in humid rooms, and dust should be controlled because small amounts stain other products and equipment. Shelf life is set by the supplier, with total color and appearance retested once past the retest date. Keep each container's FDA certification lot number with the stock so it can be traced into finished batches.
Lots and expiry dates
Record the FDA certification lot number and total color of each lot of D&C Red No. 33, and adjust dosing when dye content differs from the previous lot. Compare shade against a retained standard in the finished product, since subsidiary-color and particle-size differences can shift hue.
Regulatory status
Facts from regulators and standards bodies, each linked to its source.
21 CFR 74.1333 limits D&C Red No. 33 in ingested drugs, other than mouthwashes and dentifrices, to 0.75 mg per daily dose.
Source: ecfr.gov (opens in a new tab)21 CFR 74.2333 limits D&C Red No. 33 in cosmetic lip products to 3 percent total color by weight of the finished product.
Source: ecfr.gov (opens in a new tab)21 CFR 74.2333 permits D&C Red No. 33 in mouthwashes, dentifrices and externally applied cosmetics in amounts consistent with good manufacturing practice.
Source: ecfr.gov (opens in a new tab)All batches of D&C Red No. 33 must be certified by FDA under 21 CFR part 80.
Source: ecfr.gov (opens in a new tab)
This is general information, not regulatory advice. Status differs by country and by how the ingredient is used, so check the rules for your product and market.
D&C Red No. 33 suppliers
Manufacturers and distributors whose own websites say they sell it.
We are checking d&c red no. 33 suppliers now
Every listing is checked against the supplier’s own website before it goes live, so this list fills in over the coming weeks. The specs and COA checklist above are ready today.
Sell d&c red no. 33? Request a listingFrequently asked questions
What forms of d&c red no. 33 can brands buy?
Common forms include straight color powder, aluminum lake, liquid solution and pre-mixed shades. Ask each supplier for the specification sheet of the exact grade they quote.
What should the COA for d&c red no. 33 include?
Expect fDA certification lot number, total color, volatile matter and salts, aromatic amines and intermediates, heavy metals and shade and strength vs. standard, each with its method, specification and result for that lot.
How should d&c red no. 33 be stored?
Store in the original sealed containers in a cool, dry place away from light and heat; powders cake in humid rooms, and dust should be controlled because small amounts stain other products and equipment. Shelf life is set by the supplier, with total color and appearance retested once past the retest date. Keep each container's FDA certification lot number with the stock so it can be traced into finished batches.
What is the regulatory status of d&c red no. 33?
21 CFR 74.1333 limits D&C Red No. 33 in ingested drugs, other than mouthwashes and dentifrices, to 0.75 mg per daily dose. 21 CFR 74.2333 limits D&C Red No. 33 in cosmetic lip products to 3 percent total color by weight of the finished product. 21 CFR 74.2333 permits D&C Red No. 33 in mouthwashes, dentifrices and externally applied cosmetics in amounts consistent with good manufacturing practice. All batches of D&C Red No. 33 must be certified by FDA under 21 CFR part 80.
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