Sulfites are compounds that contain the sulfite ion. The sulfite ion is the conjugate base of bisulfite. Although its acid is elusive, its salts are widely used. Sulfite is used in the photography industry to protect developing solutions from oxidation, in the pulp and paper industry, in water treatment as an oxygen scavenger agent, as a desulfurizing and dechlorinating agent in the leather industry and as a bleaching agent in textile industry. Sodium sulfite is a component in many pharmaceuticals, which is effective to maintain the potency and stability of drugs. It is added to a number of drug preparations as an antioxidant and antimicrobial agent. Sulfite is used as a food preservative. Topical, oral or parenteral exposure to sulphites has been reported to induce a range of adverse clinical effects in sensitive individuals, ranging from dermatitis, urticaria, flushing, hypotension, abdominal pain and diarrhoea to life-threatening anaphylactic and asthmatic reactions. Exposure to the sulphites arises mainly from the consumption of foods and drinks that contain these additives; however, exposure may also occur through the use of pharmaceutical products, as well as in occupational settings. Sulfite is accepted for use as a food additive in Europe. Sodium sulfite is generally recognized as safe by FDA. It is included in FDA Inactive Ingredients Database (epidural, IM, IV, and SC injections; inhalation solution; ophthalmic solutions; oral syrups and suspensions; otic solutions; topical creams and emulsions). Included in nonparenteral medicines licensed in the UK.