Eyelash extensions are intended to add length, thickness and fullness to natural eyelashes, which can be separated into two types: temporary and semi-permanent. Becoming more and more popular, semi-permanent eyelash extensions will give you longer, thicker and very natural looking eyelashes, making the eyes seem to shine and brighten with light like diamond. However, there are also some disadvantages of eyelash extensions. First of all, in most cases, it can take one to two hours for people to well apply the eyelash extensions. Secondlt, usually it will cost a lot of money. In addition, it still requires much extensive maintenance to replace them every six to eight weeks and make a few modifications to keep them from coming off. For example, you must use water-based mascaras and avoid using any makeup removers or makeup products that contain oil, since these can loosen the adhesive holding the false lashes in place. Last but not least, the eyelash extensions can make your lashes become noticeably sparser and become brittle as well and break off, appearing much shorter. On the other hand, there are also some common allergic reactions.