Frown lines, or glabellar lines, are vertical lines that appear between the eyebrows. These wrinkles appear over time from the effects of sun exposure, age, and habitual frowning due to tension. As a person ages, the skin becomes less elastic and the glabellar lines become more pronounced. In some cases, they stay permanently in the face, making it appear that the person is always frowning or angry. You may feel that in addition to being aging, these lines make you appear tired or grumpy when you’re nothing of the sort!