Lopsided Smile: Everything You Need to Know

It can be a long-term or short-term problem

A crooked or uneven smile is fairly common—most people do not have complete symmetry to their face. However, some medical problems can cause a lopsided smile, and this can be a sign of a medical emergency. There are many possible reasons for a lopsided smile, and most are not dangerous. However, a sudden change requires urgent medical attention.

This article will discuss causes of a lopsided smile, the significance of a sudden lopsided smile, and when to see a healthcare provider.

Healthcare provider checking person for lopsided smile

Halfpoint Images / Getty Images

Lopsided Smile Causes

The causes of an uneven smile vary and include issues like dental problems, nerve damage, stroke, and more. Usually, the different causes are associated with additional symptoms besides a crooked smile. 


A stroke is a serious type of brain damage that occurs due to an interrupted blood supply in an artery of the brain. Among other symptoms, it can cause weakness of the face and body on one side.

Symptoms from a stroke appear suddenly and it is a medical emergency. The acronym "FAST" stands for facial drooping, arm weakness, speech difficulties, and time to call emergency services.

Bell’s Palsy

This type of facial weakness or paralysis affects one side of the face. Common symptoms affecting the mouth are that one corner of your mouth will droop and the smile line (nasolabial fold) will disappear. There will also be weakness in the forehead, eyelid, and cheek on that side of the face.

Bell's palsy develops over the course of a few hours and worsens for a few days. After a couple of weeks, it begins to improve gradually, often taking three to six months to get back to normal.

The causes of Bell's palsy are not known. It often improves on its own, and sometimes oral steroids can help speed up recovery.

Facial Paralysis

Facial movements can become paralyzed (weak) due to nerve or muscle damage. Besides Bell’s palsy, stroke, and nerve injury, a few other causes of facial weakness include:

  • Myasthenia gravis: A condition in which the immune system mistakenly attacks receptors needed to activate muscles
  • Multiple sclerosis: A condition in which the immune system mistakenly attacks the protective myelin sheath of nerves in the brain, spinal cord, and eyes
  • Amyotrophic lateral sclerosis: A disease that attacks the nerves that control movement

Uneven Teeth 

Many people naturally have mildly or moderately uneven teeth. This typically does not cause a crooked smile. Sometimes teeth are naturally very uneven or become severely uneven due to dental conditions such as tooth decay. This can cause a smile to appear crooked. 

Misaligned Jaw

The jaw structure can cause a lopsided smile if the bones or movement of the jaw are formed unevenly or become damaged due to trauma or disease (such as cancer invading the bone). 


Surgery may cause damage to the nerve branches that control mouth movements. This can occur when surgery is necessary for removal of a tumor or abscess that has grown into the facial nerve. And sometimes a surgical error can result in accidental transection (cutting) or a nerve or nerve branch. 


For some people, aging can lead to an uneven smile. This can occur as a result of wrinkles, dental issues, nerve damage, or stroke. 


Smoking may lead to mouth diseases, such as severe tooth decay, gum disease, or oral cancer. This can cause a crooked smile. 


An injury to the face can cause damage to the nerves, muscles, bones, or other tissues. Swelling can be substantial as well. This can cause a lopsided smile and an uneven appearance of the face.

After the swelling goes down and healing is complete, the face and smile can partially or fully return to normal. With severe trauma, a crooked smile can remain for the long term. 


Torticollis is a movement disorder that causes involuntary (not on purpose) spasms and twisting of the neck. The muscles can spasm for prolonged periods, sometimes resulting in a crooked smile. This condition may be present from birth and can be associated with certain birth defects.

Associated Symptoms

Symptoms associated with a lopsided smile can include:

  • Flattening of the nasolabial fold (the angled crease at the bottom of your cheeks, near your nose)
  • Slurred speech
  • Trouble chewing or swallowing
  • A droopy eyelid
  • An eyelid that can’t fully close

Sudden Lopsided Smile

A sudden lopsided smile can be a sign of a stroke, brain aneurysm (a bulge in the wall of an artery), or an infection. This may develop over the course of hours. Rarely, a new and rapidly worsening lopsided smile can be a sign of a tumor, cancer metastasis (spreading of cancer), or a seizure (uncontrolled electrical activity in the brain).

What to Do If You Think Someone Is Having a Stroke

If you think someone is having a stroke, call 911 and stay with them until emergency help arrives. If possible, describe what you witnessed when emergency healthcare providers arrive.

When to See a Healthcare Provider

If your face or mouth suddenly feels numb or if movement seems uneven, this means that you should get medical attention right away. 

Symptoms associated with an uneven smile that require urgent medical attention include: 

  • Sudden, severe headache
  • Weakness on one side of the body
  • Loss of balance
  • Vision changes 
  • Facial drooping on one side 
  • Slurred speech 
  • Traumatic injury
  • Swelling of the face or neck 
  • Inability to control facial movements 
  • Spasms of the face or neck 
  • Pain of the eye or an infection of the eye 


There are different techniques that can be used for treatment of an uneven smile. Immediate treatment differs from delayed treatment. 

During an emergency situation, such as a stroke or severe facial trauma, the immediate treatment involves preventing serious damage and reducing the long-term effects. This may include interventions such as blood thinners for stroke treatment or surgery for treatment of facial trauma. 

After a lopsided smile has stabilized, treatment can include exercises to train the muscles. This can be directed to improve the facial appearance, as well as to prevent complications, such as choking. 

In some situations, injections of Botox (botulinum toxin) can work to paralyze certain muscles to prevent a crooked appearance of the mouth.

And sometimes surgical intervention may be necessary to reconstruct the facial nerves, muscles, bone, or other structures. This can help to even out the appearance of the face. This type of surgery may also be effective for reducing the risk of certain complications, like eye damage due to an eyelid that doesn’t properly close. 


A crooked smile can be the result of different medical problems. Sometimes, a person’s smile is uneven due to normal variations, and it isn’t usually anything to worry about. But sometimes, a lopsided smile can be a sign of a serious medical issue, such as a stroke or an infection.

It’s important to get prompt medical attention for any sudden change in facial appearance. Other causes, such as Bell’s palsy or a misaligned jaw, may need medical intervention and management to prevent complications. 

A Word From Verywell 

An uneven, or lopsided, smile can range from barely noticeable to profoundly affecting safety, self-esteem, and quality of life. Your feelings about your appearance are important, and there are ways to manage an uneven smile, including physical rehabilitation, medication, and surgery. 

Frequently Asked Questions

  • What are the initial signs of Bell’s palsy?

    Generally, Bell’s palsy starts with stiffness or weakness of the face, including the eyelids. Blinking your eyes may feel uneven, or you might have a sensation of dryness in one of your eyes. Sometimes it can be hard to chew on one side, and your smile looks very uneven.

    The condition usually causes profound paralysis of one side of the face, including an inability to raise your eyebrow on one side. With Bell’s palsy, the face moves unevenly, and the sides of the face look uneven while you are resting your face.

  • When should I be concerned about a sudden lopsided smile?

    You should get medical attention if it is new, if it happens suddenly, or if the unevenness is severe. Complications can also be concerning, even if the cause is not dangerous.

    Complications may include corneal damage (to the outer layer of your eye), visual problems (due to a droopy eyelid), and the risk of choking due to chewing and swallowing problems.

  • What are the signs of a stroke?

    Common signs of a stroke include sudden weakness of one side of the face and/or body, trouble speaking or understanding language, loss of balance, dizziness, or confusion. Get prompt medical attention if you or someone else experiences these symptoms.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Stroke signs and symptoms.

  2. MedlinePlus. Bell palsy.

  3. Johns Hopkins Medicine. Bell's palsy.

  4. De Stefani E, Barbot A, Bertolini C, et al. A new neurorehabilitative postsurgery intervention for facial palsy based on smile observation and hand-mouth motor synergies. Neural Plast. 2021;2021:8890541. doi:10.1155/2021/8890541

  5. Yoshimoto S, Sato N, Kuroki T, Rikihisa N, Ichinose M. Static reconstruction of malar region in facial paralysis: a new alternative technique for plasty of symmetric mouth appearance. J Plast Surg Hand Surg. 2013;47(5):390-3. doi:10.3109/2000656X.2013.771584

  6. Kuo AA, Tritasavit S, Graham JM Jr. Congenital muscular torticollis and positional plagiocephaly. Pediatr Rev. 2014;35(2):79-87; quiz 87. doi:10.1542/pir.35-2-79

By Heidi Moawad, MD
Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.