The Facts

Metal hypersensitivity is a disorder of the immune system. It is a common condition that affects 10% to 15% of the population. It can produce a variety of symptoms, including rashes, swelling, or pain due to contact with certain metals (see the symptoms and complications section, below).

In addition to the local skin reactions, metal hypersensitivity can also manifest itself as more chronic conditions such as fibromyalgia and chronic fatigue syndrome. There are numerous local and systemic symptoms that, when considered together, can be caused by metal hypersensitivities.

It is estimated that up to 17% of women and 3% of men are allergic to nickel and that 1% to 3% of people are allergic to cobalt and chromium. These types of reactions can be localized reactions that are limited to one area, but they can also be more generalized and affect other more distant parts of the body.

Causes

The symptoms of metal hypersensitivity are caused when the body's immune system starts to view metal ions as foreign threats. The cells that make up the immune system normally kill foreign bacteria and viruses by causing inflammation. If they begin attacking metal ions that you touch, eat, inhale, or have implanted in you, they can produce a variety of symptoms (see the symptoms and complications section, below).

Potential metal allergens (triggers of allergic reactions) are very common in everyday life. Typical sources such as watches, coins, and jewellery come readily to mind. However, there are also other less obvious sources of metal in our daily lives. For example, cosmetic products and contact lens solutions may also contain metals that can trigger a reaction at the area of contact.

Nickel is one of the most frequent allergens, causing significant local contact dermatitis (skin reddening and itching). Cobalt, copper, and chromium are also common culprits. These metals can be found in consumer items such as jewellery, cell phones, and clothing items.

Aside from everyday items, medical devices also contain possible allergens such as chromium and titanium. Older dental implants and fillings are often made of metals. A few intra-uterine devices (IUDs) for birth control are made of copper and can also cause hypersensitivities. Implantable devices such as artificial knees, artificial hips, pacemakers, stents, and fracture plates, rods, or pins may contain metals that can cause metal hypersensitivity reactions. These reactions are often more severe in nature when the allergens have been implanted within the body for an extended period of time.

In addition, people who already have an autoimmune disorder (a disorder where the immune system is overactive) can have a higher risk of a metal hypersensitivity, as their immune system is in a constant state of activity.

Symptoms and Complications

Signs and symptoms of metal hypersensitivities can range from small and localized to more severe and generalized.

Limited reactions can appear as a contact dermatitis on the skin that has been exposed to the metal. The skin may appear red, swollen, and itchy. Hives and rashes may also develop.

More severe metal hypersensitivity reactions usually occur from prolonged exposure to a metal allergen through implants or metal ions that are inhaled or eaten. These reactions often cause chronic joint or muscle pain, inflammation, and swelling, leading to generalized fatigue and lack of energy. In addition, fibromyalgia (pain without known cause) and chronic fatigue syndrome can also be seen in people with metal hypersensitivities.

Common symptoms of metal hypersensitivity include:

• blistering of the skin
• chronic fatigue
• chronic inflammation
• cognitive impairment
• depression
• fibromyalgia
• hives
• joint pain
• muscle pain
• rash
• reddening of skin
• swelling

Related conditions

The following symptoms and conditions have been linked to metal hypersensitivity. If you have any of these conditions, you may wish to speak to your doctor about the possibility of a metal hypersensitivity:

• chronic fatigue syndrome
• eczema
• fibromyalgia
• osteomyelitis
• rheumatoid arthritis

Making the Diagnosis

Your doctor may suspect metal hypersensitivities based on a combination of your personal history and your signs and symptoms. To determine possible causes of metal exposure, your doctor may ask if you have any type of implants, if you smoke, or if you regularly use any cosmetics.

Aside from a thorough personal history, your doctor may also order laboratory tests to confirm whether you have a metal hypersensitivity. These tests usually involve giving a blood sample at a laboratory. The laboratory technicians will test the white blood cells for their activity against metal ions by using radioisotopes and microscopically observing physical changes within the cells. If the test shows that the white blood cells have increased activity when exposed to the metal ions, it indicates the presence of a metal hypersensitivity.

A dermatologist can also conduct an allergy test in which they expose various metal ions to your skin to test for a hypersensitivity reaction. This allergy test, which is similar to a regular "scratch test," is often done as a "patch test." The metal ions that are believed to be causing the allergic reaction are applied to a patch, which is then placed on the skin. The patch is left in place for 48 hours, after which it is removed from the skin at a return visit to the doctor. Skin that is red or irritated under the patch may be an indication of an allergy.

Treatment and Prevention

Treatment of metal hypersensitivity is highly individualized, as the allergens and reactions can be very different from person to person.

Skin hypersensitivities can often be resolved by avoiding the item that causes the reaction. If the dermatitis is more significant, the doctor can also prescribe corticosteroid creams and ointments to reduce the local inflammation. The doctor can also prescribe oral antihistamines to further reduce the allergic reaction. Oral corticosteroids can also be used, but they can cause problematic side effects.

Systemic reactions are more difficult to resolve, as they are often caused by implants. Removal of the implant is sometimes considered when a non-metal replacement is available and may be used. For example, a plastic-based dental filling material may be used to replace a previous metal dental filling. However, if the allergy is caused by an artificial knee or hip, replacement with a non-metal option is rarely done due to the difficulty of replacement. For these situations, treatment usually involves both topical (surface-applied) and oral medications to reduce the allergic reaction. Due to the difficult nature of treating systemic metal allergies, doctors sometimes recommend a hypersensitivity test before an implant is chosen.