In general, eyelash extensions are not considered dangerous, although there can be some side effects. Some women may experience damage and loss of their natural lashes, others can have an allergic reaction, and there is also the possibility of infection. To minimize your risks, you should always do your research beforehand and pick a reputable salon and skilled technician. It is also advisable to opt for lashes that are not too long or heavy, as this can further increase any complications.