By DR. JESSICA NOONAN

Who doesn't love money? A little jingle in your pocket usually brings a smile to the face. But two new coins in the United Kingdom might leave some people literally itching to get away from them.

The UK has decided to coat their 5p and 10p coins with nickel, a material that causes a skin reaction similar to that seen with poison ivy in some people.

Specifically, people who have a skin allergy to nickel may develop an allergic contact dermatitis when they come in contact with the metal. This means that handing the new coins could lead to a skin rash consisting of redness, swelling and itching for those unfortunate enough to have this allergy.

According to two dermatology experts in the U.K. who wrote a report appearing online in BMJ on Thursday, these people may even be at increased risk for hand eczema, a condition in which the palms become inflamed and covered in itchy, potentially painful blisters.

The coins' composition is being changed as a cost-cutting measure, but the authors say the cost to treat those affected by allergic reactions might be steep. They contacted Britain's HM Treasury asking for data on the amount of nickel that is released from the new coins onto the hands.

According to Dr. Danielle Greenblatt, co-author of the letter and specialist registrar in dermatology at the Guy's and St. Thomas's MHS Trust in London, the treasury admitted it did not have answers to her questions.

"There hasn't been any research that I'm aware of on these new coins to show what effect they may have," says Greenblatt.

Last year Sweden decided not to use nickel in their coins based on the results of research by Professor Carola Lidén at Karolinska Institutet in Stockholm.

"The studies show that several coin alloys that contain nickel give off significant quantities of nickel to the skin already after relatively brief contact," reads the report from the Swedish Riksbank's 'Bank Note and Coin Project' in 2011.  It concludes: "Nickel should not be used in the new coins because of the allergy risk."

Nickel is one of the most common skin irritants in the world. Five percent of men and 27 percent of women had a reaction to nickel in a skin patch allergy test performed in a 2007 Norwegian study of more than 1,200 people.

Nevertheless, nickel is currently used in coins around the world.  Typically it's part of a mixture of metals, called an alloy, with nickel representing 5 to 25 percent. According to the U.S. Mint, the American nickel, dime and quarter are all composed of a copper-nickel alloy.

These new British coins are different since they would be coated in pure nickel rather than having the metal simply mixed in. This actually reduces the total amount of nickel in the coin, down to 2 or 3 percent, but it means that the entire surface of the coin - the part that comes into contact with the skin - would be made of nickel.

Not everyone is worried. Andrew Mills, director of circulating coin at the Royal Mint, says that nickel-plated coins are currently in circulation in over 30 countries worldwide, and the coins being replaced already contain nickel in the alloy form.

An official statement released by the Royal Mint reads, "[The Royal Mint] can confirm that the new nickel-plated 5p and 10p coins have no additional potential to cause adverse effects on people with allergic contact dermatitis and hand dermatitis."

Dermatology and allergy experts in the U.S. agree that there is a low likelihood for reactions.

"It usually requires more extended contact than just handling a coin, such as wearing  jewelry or belt buckles," says allergist Dr. James L. Sublett, American College of Allergy Asthma and Immunology fellow and spokesperson.

"The main risk is to people who handle a lot of coins and would most likely be in occupations that make a lot of change."

Dr. Anthony A. Gaspari, chief of dermatology at University of Maryland Medical Center in Baltimore, says he rarely sees any reactions to the U.S. coins.

"Occasionally we'll see a problem with a patient who keeps coins in their pocket all day and they sweat and the nickel leaches into the skin through the fabric causing irritation," Gaspari says. "But that's not very common."

Gaspari says even though the new coins will be completely coated in nickel, he would still expect that prolonged contact with the skin would be required to cause any sort of reaction.

Only time will tell what effect these new coins will have, as no research is planned. The Royal Mint says a limited quantity of the coins are already in circulation with the remainder to be released soon.

Scott A. Travers, coin expert and author of "The Coin Collector's Survival Manual" and R.W. Julian, Coin Researcher, contributed background information for this article.