There are currently more than 100 dyes and colouring agents approved by the Food and Drug Administration (FDA) for use in pharmaceutical preparations (Med Toxicol, 1988; 3: 128-65). Most oral liquid formulations contain between one to three different dyes.

Exposure to dyes and colorants in medications has been associated with a range of hypersensitivity reactions. These can occur in anyone, but may be particularly severe in those for instance, the 2-20 per cent of asthmatics who are also aspirin intolerant.Individuals who react to aspirin with the classic triad of symptoms asthma, hives and rhinitis or who experience anaphylactoid (shock) reactions may also develop bronchoconstriction, localised vascular oedema, hives, abdominal pain and vomiting, and contact dermatitis on ingestion of the following dyes and colorants:

Amaranth New coccine

Brilliant blue Ponceau

Erythrosine Sunset yellow\

Indigo carmine Quinolone yellow

Methyl blue Tartrazine

Skin reactions including photosensitivity, skin rashes and peeling have been associated with erythrosine, an iodine containing dye (Contact Dermat, 1978; 4: 305). Erythrosine has been removed from topical products and is being voluntarily removed from many oral drug products because of concerns about carcinogenicity. However, many other dyes can cause skin reactions like contact dermatitis. These include:

D&C yellow no. 11

Gentian violet

Indigo carmine

Neutral red

Quinoline yellow

Some parents and clinicians believe there is link between dyes, and hyperactivity and aggressive behaviour in children, although this has not been borne out in controlled clinical trials (Pediatrics, 1985; 76: 635-43; Ann Allergy, 1977; 38: 206-10).

\Sunset yellow has also been associated with gastrointestinal intolerance, abdominal pain, vomiting and indigestion (Lancet, 1982; ii: 385; Ann Intern Med, 1989; 111: 87-8).