Thin lips are lips that have less volume and definition compared to fuller lips. Some people are born with naturally thin lips, while others may experience thinning of the lips due to aging or other factors such as smoking or sun damage.

Here are some common causes:

Genetics: The shape and size of your lips are largely determined by your genes. If your parents have thin lips, you are more likely to have them too.

Aging: As you age, the production of collagen and elastin in your body decreases. These are the proteins that give your skin its elasticity and plumpness. This can cause your lips to lose volume and become thinner.

Sun exposure: Exposure to the sun’s harmful UV rays can damage the collagen and elastin in your lips, leading to thinning and wrinkles.

Smoking: Smoking can cause your lips to become thinner and darker over time, as the chemicals in cigarettes can damage the collagen and elastin in your skin.

Dehydration: Not drinking enough water can cause your lips to become dry, cracked, and thin.