“Eyelash hair loss happens for a multitude of reasons,” says Paul Jarrod Frank, MD, a cosmetic dermatologist in New York City and author of The Pro-Aging Playbook. “It can be a sign of using the wrong products, a signal you’re under tremendous stress, or a result of removing false eyelashes improperly, but it can also signal a more systemic health issue.” Keep reading for more reasons your eyelashes could be falling out and when to see a doctor for a proper evaluation.

Common Reasons for Eyelash Hair Loss

As with any bodily change, the key to a solution is getting to the root of the problem. Before you go down a WebMD rabbit hole and self-diagnose yourself with a serious disease, there are more likely reasons you should rule out first. Just like the hair on your head, eyelashes naturally fall out and replace themselves in a natural cycle every six to 10 weeks, so it’s totally normal to lose between one and five eyelashes each day. Thinning eyelashes are another part of the aging process, so if your lashes don’t seem to have the same length and fullness they once did, don’t worry. Most of the time, some shedding and thinning are completely natural and nothing to worry about. If the volume of hair loss is more significant, dermatologists say these are the most common culprits.

Excessive Rubbing and Friction

It’s important to keep your eye area clean from debris (especially when it comes to removing your makeup before bed), but experts caution that cleansing such a sensitive area should come with great care. “You’ll want to steer clear of any trauma to the lashes, avoiding heavy rubbing, tugging, and excessive force, especially along the eyelid margin,” says Jenny Liu, MD, a board-certified dermatologist and assistant professor at the University of Minnesota. A common culprit behind eyelash friction is your sleep mask. According to Clementina Richardson, a celebrity lash expert and founder of Envious Lashes, a sleep mask can cause eyelash extensions to lean and lose their shape from being pressed against your eyes all night. To ensure the mask isn’t too tight on your face, look for sleep masks that are adjustable or designed for lash extension wearers.

Bacterial Infection (from expired makeup)

If you’re not paying attention to your makeup expiration dates, that might be the culprit behind your hair loss. Dr. Frank points out that you’ll especially want to pay close attention to the expiration dates on your eye products, as this can often lead to bacterial infection.“Mascara should be discarded every three months, as it’s prone to accumulating staph. A bacterial infection from expired products can cause inflammation, thus resulting in a loss of eyelashes.”

Allergic Reactions

While you’re at it, do yourself a favor and check the label’s ingredient list. “Allergies to cosmetics, eye makeup, makeup remover, skincare, and even nail polishes are common causes of eyelid dermatitis and, if severe, can cause eyelash loss,” warns Dr. Liu. If you suspect the eyelash loss is from a reaction to cosmetics or eye cream, stop using eye products and get an allergy test to find out what you’re allergic to.

False Lashes

Then there are false lashes, which represent a range of culprits combined. “When it comes to extensions, many people have an allergic reaction to the glue, resulting in inflammation that can cause eyelashes to fall out. In the case of false lashes, the glue can bind to natural lashes and, if taken off improperly, can rip out the natural lashes,” says Dr. Frank. He suggests using a specific adhesive remover or an oil cleanser for more gentle removal.

When to See a Specialist

If you’ve ruled out the above and the problem still persists, it may be time to see a physician to look into underlying conditions. It’s more concerning if lashes fall out on both lids, which could indicate a more systemic problem," advises Dr. Frank. If you’re noticing accompanying hair loss on the eyebrows and/or the scalp, or you also have skin changes like itching, redness, or scaling, this may be a sign of a health problem or condition. Below are reasons for eyelash hair loss that warrant a doctor’s visit.

Thyroid Disorders

Dr. Frank notes the thyroid gland controls the body’s hormones, and that changes in those hormones from an overactive (hyper) or underactive (hypo) thyroid can lead to eyelash loss. “Additional symptoms can vary, including weight loss or gain, difficulty controlling temperature, increased anxiety, and constipation, and are generally addressed with an endocrinologist evaluation and subsequent medication.”

Blepharitis

“Blepharitis is a condition characterized by clogged glands that cause inflammation and trigger loss of eyelashes. It’s frequently driven by the bacteria that reside along the lash line,” explains Audrey Kunin, MD, a board-certified dermatologist, chief product officer of NovaBay Pharmaceuticals, and founder of DERMAdoctor. “Eyelids may look crusty and inflamed, red, and watery, and feel gritty. In terms of treatments, Avenova Lid & Lash Spray ($30; amazon.com) contains hypochlorous acid, which is gentle to the eye area yet effectively treats blepharitis at its source, killing bacteria responsible for the inflammation.”

Trichotillomania

“Trichotillomania is a condition where a person pulls out their eyelashes due to emotional stress. It can also be genetic,” says Dr. Frank. Commonly referred to as a hair-pulling disorder, research suggests that about one out of 50 people will experience trichotillomania in their lifetime, with compulsive behaviors usually beginning in late childhood or early puberty and often addressed through therapy and/or medication. See a therapist who can prescribe medications and treatments for impulse control disorders such as this.

Certain Cancers

While rare, Dr. Kunin notes that localized skin cancers of the eyelids can lead to lash loss, as cancer affects the hair follicles. “Any non-healing sores, scans, or crusting should be signs to have your eyes examined.” If you have any of these, see your doctor right away.