An acupuncture pen delivers a small electric current to an acupuncture point instead of a needle being placed into it. There are many different types of pen available to buy, but they all work on the same principle, that of so-called electro-acupuncture. Some acupuncturists will insert a needle and then apply an electric current to it during an electro-acupuncture treatment. However, pens work slightly differently because they apply the electricity to the selected point without the need to penetrate the skin. Some studies have noted a reduced amount of nausea among people who use them, especially when they have been taking a drug therapy that has been unsettling them. The US Food and Drug Administration tested some pens and found that there was little to recommend them, however. In fact, they warned about potential tissue damage caused by their repeated use. Nevertheless, some people consider them to be completely harmless.