Thimerosal Allergies in Adults

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contact dermatitis

Thimerosal is an organic chemical composed of mercury and thiosalicylate. It has been used for many years as an antibacterial and antifungal preservative in vaccines and other biological products. Some of the products that are preserved using thimerosal include cosmetics such as mascara, eye shadows and makeup remover; and personal hygiene items such as antiseptic sprays, soap-free cleansers and topical medications. Lately, thimerosal use is declining owing as it triggers allergies in some people.

How Thimerosal Works In the Body

Thimerosal contains a type of mercury known as ethylmercury, the compound that triggers allergic reactions in some adults. This compound differs from methylmercury and elemental mercury which are found in certain fish species and in the environment. Elemental mercury and methylmercury are present in the human body and can be toxic when they build up to high levels, notes the

Food and Drug Administration

. However ethylmercury clears out of the blood quickly, hence it does not accumulate to harmful levels. When thimerosal enters the human body, it breaks down to ethylmercury and thiosalicylate, which are excreted easily.

Effects of Thimerosal

Thimerosal triggers a condition known as allergic contact dermatitis, which is characterized by red, itchy patches, swelling, blisters, and localized discomfort at the spot where a person is injected with thimerosal. Almost all reactions are usually mild, and usually go away after a few days. The hypersensitive reactions may be due to the thiosalicylate or mercury elements of thimerosal. The high number of reported cases of thimerosal allergies has fuelled research and production of vaccines and other products that contain no thimerosal.

Thimerosal Allergy Tests

Thimerosal allergy can be diagnosed by conducting a special test known as Thin-Layer Rapid use Epicutaneous test. This is a patch test that exposes you to 0.1% thimerosal in aqueous solution. A person who is allergic to thimerosal will develop topical irritation on the affected part.

Treatment for Contact Dermatitis

If you’ve tested positive to thimerosal allergy, avoid exposure to products that contain thimerosal. The treatment of the contact dermatitis is similar to that of any other acute dermatitis and eczema. This involves ingesting oral antihistamine or topical application of hydrocortisone on the affected part.

Avoiding Thimerosal

Once you have been diagnosed with thimerosal sensitivity, you should avoid contact with any product that has been preserved with thiomersal. Make sure you read product labels and watch out for alternative names for thimerosal such as thiomersal, thiomersalate, thiomersalan, Merthiolate, mercurochrome, sodium ethylmercurithiosalicylate, Ethyl (2-mercaptobenzoato-S) mercury sodium salt and mercurothiolate. If you are unsure, ask your pharmacist for assistance.

Whenever you are being treated or vaccinated against a certain medical condition, inform your doctor that you’ve got a thimerosal allergy. If available, your doctor should administer vaccines that contain no thimerosal. However, if no alternatives are available, discuss the potential risks of being vaccinated or treated with a vaccine that contains thimerosal against its benefits with your doctor. Normally, an allergic reaction triggered by thimerosal isn’t as risky as the consequences that may result from not being vaccinated. If you are highly allergic to thimerosal, your doctor can prescribe alternative treatment options.

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