Lip smacking has a surprisingly wide range of causes, from dry mouth and nervous habits to medication side effects and neurological conditions, and the right way to stop it depends entirely on why it is happening. For some people it is a simple behavioral pattern tied to stress or dehydration; for others it is an involuntary movement triggered by certain prescription drugs. Understanding the underlying cause is the first step, because the solutions range from a tube of lip balm and better hydration all the way to FDA-approved medications that target brain chemistry.
Why People Smack Their Lips in the First Place
Lip smacking is not a single condition with a single fix. It is a symptom that shows up across a wide spectrum of situations, and lumping every case together leads to the wrong treatment. The causes broadly fall into three categories: habitual or behavioral, physiological, and neurological. Habitual lip smacking tends to stem from dry lips, mouth breathing, dehydration, or a stress-related oral habit that became automatic over time. Physiological causes include anything that dries out the mouth or irritates the lips, from certain medications to environmental conditions. Neurological lip smacking is the most medically significant variety and involves involuntary repetitive movements of the mouth, jaw, and tongue driven by changes in how the brain controls motor function.
Teasing these apart matters because the treatments are completely different. A person who smacks their lips out of habit during moments of anxiety needs a behavioral approach. A person whose lips smack involuntarily after months on an antipsychotic medication needs medical intervention. And someone who just has chronically dry lips needs practical skincare adjustments. The sections below break each cause down and walk through what actually works.
Dry Mouth and Dehydrated Lips
The most common and least worrying cause of lip smacking is simply dry lips or a dry mouth. When the mucous membranes around your lips lose moisture, you instinctively lick, press, or smack your lips together to spread whatever saliva is available. That momentary relief reinforces the behavior, and before long the smacking becomes habitual even when your lips are not particularly dry. The irony is that repeated licking actually makes things worse: saliva evaporates quickly and takes moisture from the lip surface with it, leaving the skin drier and more irritated than before.
Chronic lip licking can escalate into a recognized skin condition called lip-licking dermatitis (or cheilitis simplex). Patients develop redness, peeling, cracking, and sometimes secondary infections around the lip margins. Practical steps to break this cycle include applying a bland lip balm with UV protection, staying well hydrated, shielding the lips from cold or windy weather, and recognizing when the skin is already inflamed enough to need a dermatologist’s help.1PubMed Central. Art of prevention: Practical interventions in lip-licking dermatitis In one case study, a patient whose chronic lip-licking habit was tied to psychological stress was treated with a topical ointment and given a stress ball to redirect the urge.2PubMed Central. Lip-Lick Cheilitis and Its Connection to the Brain That combination of treating the skin irritation while also addressing the behavioral trigger is the general blueprint for this category of lip smacking.
If dry mouth itself is the problem rather than just dry lips, saliva substitutes and natural sialogogues (substances that stimulate saliva production) can help. A clinical trial comparing artificial saliva sprays with citric acid lozenges found that both provided immediate relief from oral dryness, but citric acid gave a longer-lasting sense of moisture because it continued to stimulate the salivary glands for at least an hour after use.3Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology. A comparison of salivary substitutes versus a natural sialogogue (citric acid) in patients complaining of dry mouth as an adverse drug reaction Sugar-free gum and sour candies work on the same principle. If you are on a medication known to cause dry mouth, ask your prescriber whether adjusting the dose or switching drugs is feasible.
Medication-Induced Lip Smacking and Tardive Dyskinesia
This is the cause that deserves the most attention, because it is both common and potentially serious. A class of involuntary mouth movements called tardive dyskinesia (TD) can develop in people who take certain medications, particularly antipsychotics and the anti-nausea drug metoclopramide. TD shows up as repetitive, involuntary movements of the face: lip smacking, lip puckering, chewing motions, and tongue protrusion are the hallmark signs.4PubMed Central. Antipsychotic-Related Movement Disorders: Drug-Induced Parkinsonism vs. Tardive Dyskinesia-Key Differences in Pathophysiology and Clinical Management The “tardive” in the name means delayed: symptoms typically appear after at least three months of treatment, and sometimes much longer.
TD can develop with both older (“typical”) and newer (“atypical”) antipsychotics. There is a lingering misconception that only older drugs like haloperidol cause it, but case series have documented TD in patients taking newer medications as well, and the condition can be disfiguring and potentially irreversible.5PubMed Central. Tardive dyskinesia in patients treated with atypical antipsychotics: case series and brief review of etiologic and treatment considerations Metoclopramide, which is widely prescribed for nausea and gastroparesis, accounts for close to a third of all drug-induced movement disorders and carries its own risk of tardive dyskinesia with chronic use.6Nature Clinical Practice Gastroenterology & Hepatology. Drug Insight: from disturbed motility to disordered movement—a review of the clinical benefits and medicolegal risks of metoclopramide
If you have been taking any of these medications and notice new, involuntary lip-smacking or chewing movements, do not ignore them and do not stop the medication on your own. Abruptly discontinuing antipsychotics can cause serious withdrawal effects or a psychiatric relapse. Instead, report the symptoms to your prescribing doctor promptly. Early detection matters because TD caught early is more likely to improve if the medication regimen is adjusted.
FDA-Approved Treatments for Tardive Dyskinesia
For years, there was no good pharmaceutical treatment specifically designed for TD. That changed in 2017 when valbenazine became the first FDA-approved medication for the condition, followed by deutetrabenazine. Both drugs work by blocking a protein called VMAT2, which reduces the amount of dopamine available in the motor pathways of the brain. Overactive dopamine signaling in those pathways is thought to drive the involuntary movements of TD, so dialing it down helps quiet the lip smacking, tongue movements, and jaw motions.7PubMed Central. Valbenazine for the Treatment of Adults with Tardive Dyskinesia8PubMed Central. Valbenazine and Deutetrabenazine for Tardive Dyskinesia
A meta-analysis of randomized controlled trials found that both drugs significantly outperformed placebo in reducing involuntary movement scores. Valbenazine showed a somewhat larger effect, with roughly three out of every four patients needing treatment to see one additional responder (someone whose involuntary movements dropped by at least half). Deutetrabenazine also performed well but with a slightly wider confidence interval around its results.9PubMed Central. Treatment of tardive dyskinesia with VMAT-2 inhibitors: a systematic review and meta-analysis of randomized controlled trials These medications do not cure TD outright; symptoms can return if the drug is stopped. But for people dealing with persistent involuntary lip smacking and facial movements from TD, they represent a genuine and well-studied option that did not exist a decade ago.
Seizure-Related Lip Smacking
Lip smacking is also one of the recognizable signs of a type of epileptic seizure known as a focal seizure with impaired awareness (formerly called a complex partial seizure or psychomotor seizure). During these seizures, a person may appear semi-conscious and perform repetitive, purposeless movements called automatisms. Lip smacking, chewing, and swallowing are among the most common. In a study of patients with psychomotor seizures, a small subset had prominent automatisms including lip smacking and swallowing even while maintaining some degree of responsiveness, which made the episodes easy to mistake for a voluntary habit rather than a seizure.10PubMed. Automatisms with preserved responsiveness: a lateralizing sign in psychomotor seizures
The key distinguishing feature is that seizure-related lip smacking comes in discrete episodes, often lasting under two minutes, and is typically accompanied by a period of confusion or unawareness. If someone reports episodes of lip smacking they cannot remember performing, or if a bystander notices the behavior alongside a blank stare or unresponsiveness, a neurological evaluation including an EEG is warranted. Seizure-related lip smacking is treated by managing the underlying epilepsy with antiseizure medications, not by targeting the lip movements directly.
Habitual and Stress-Related Lip Smacking
Not all lip smacking is neurological. Some people develop a habit of smacking, pressing, or clicking their lips during moments of stress, boredom, or concentration, similar to nail biting or hair pulling. These habits fall under the umbrella of body-focused repetitive behaviors (BFRBs), and they tend to operate on autopilot: you do not notice you are doing it until someone else points it out or you catch yourself mid-motion.
Behavioral treatments have the best evidence for these kinds of habits. Habit reversal training (HRT) is the most studied approach. It works by first building awareness of when and where the habit occurs (triggers, settings, emotional states) and then training a competing response, a deliberate substitute action you perform when you feel the urge. For a lip-smacking habit, that might mean pressing your tongue against the roof of your mouth, clenching your jaw gently for a few seconds, or taking a slow breath. A randomized controlled trial comparing several self-help behavioral techniques for BFRBs found that all active treatments significantly outperformed a waitlist control, with medium effect sizes, and that people who practiced multiple techniques simultaneously showed the strongest improvement.11PubMed Central. Habit Reversal Training and Variants of Decoupling for Use in Body-Focused Repetitive Behaviors. A Randomized Controlled Trial
A related technique called decoupling (DC) takes a slightly different angle. Instead of substituting a competing movement, DC redirects the habitual movement sequence partway through so that it does not complete. For lip smacking, that might mean starting the motion but then pressing your lips together firmly instead of releasing the smack. One comparison of self-help techniques found that decoupling consistently produced satisfactory results in terms of both how users felt about the technique and how much their symptoms actually improved.12PubMed Central. A Head-to-Head Comparison of Three Self-Help Techniques to Reduce Body-Focused Repetitive Behaviors HRT showed good subjective ratings but weaker objective improvement in that particular study, which suggests that combining elements of both approaches may be the most practical strategy.
Orofacial Myofunctional Therapy
If your lip smacking is connected to a broader pattern of mouth-related habits like chronic mouth breathing, lip incompetence (a tendency for the lips to hang open at rest), or an unusual swallowing pattern, orofacial myofunctional therapy (OMT) may help. OMT involves exercises that retrain the muscles of the lips, tongue, and jaw to rest and function in healthier positions. A scoping review found evidence supporting OMT’s effectiveness across a range of orofacial dysfunctions, including lip incompetence and atypical swallowing patterns.13PubMed Central. Effectiveness of orofacial myofunctional therapy in improving orofacial function and oral habits: a scoping review This type of therapy is typically delivered by a speech-language pathologist or a specially trained dental hygienist and involves daily home exercises over several weeks to months.
OMT is worth considering when lip smacking seems to be part of a larger pattern rather than an isolated habit. If you also snore, breathe through your mouth during the day, or have difficulty keeping your lips sealed at rest, the lip smacking may be a symptom of weak or poorly coordinated orofacial muscles rather than a standalone problem.
Lip Smacking in Infants and Toddlers
Parents sometimes worry when they notice their baby smacking or licking their lips. In young children, lip smacking is usually not a concern at all. It is a well-documented early hunger cue. Research on the development of feeding cues in infancy and toddlerhood explicitly categorizes lip smacking and lip licking as early signs of hunger and receptiveness to feeding.14PubMed Central. Development of Feeding Cues during Infancy and Toddlerhood When a baby smacks their lips, it typically means they are getting ready to eat or are signaling that they want to start feeding. Responding to these early cues rather than waiting for crying (a late hunger cue) tends to make feedings smoother and less stressful for both parent and child.
That said, if a child’s lip smacking is persistent, occurs at times unrelated to feeding, or is accompanied by a blank stare or unresponsiveness, it is worth mentioning to a pediatrician. As described earlier, focal seizures can produce automatisms like lip smacking even in children, and those episodes look different from the normal feeding-cue variety because they are rhythmic, involuntary, and accompanied by altered awareness.
When Lip Smacking Bothers Other People More Than It Bothers You
Sometimes the person searching for help is not the one doing the lip smacking. They are the person sitting across from the lip smacker at dinner, and the sound is driving them to distraction. If that reaction feels disproportionately intense, like genuine anger or anxiety triggered by the sound of someone smacking their lips, chewing, or clicking their tongue, the listener may have misophonia. This is a condition in which everyday orofacial sounds provoke strong negative emotional responses. Research has linked the condition to the mirror neuron system, the part of the brain that activates when you watch someone else perform an action as if you were performing it yourself. One neuroimaging study found stronger-than-normal connectivity between auditory cortex and motor areas controlling the mouth and face in people with misophonia, suggesting that trigger sounds hijack the listener’s own orofacial motor system.15PubMed Central. The Motor Basis for Misophonia
Misophonia is not an auditory disorder in the traditional sense. Hearing tests come back normal. The problem is in how the brain processes and reacts to specific sounds, with lip smacking and chewing among the most commonly reported triggers.16Frontiers in Human Neuroscience. Misophonia: physiological investigations and case descriptions If you recognize yourself in this description, knowing that the reaction has a neurological basis can be oddly reassuring. Cognitive behavioral therapy and sound-desensitization techniques have shown some promise in managing misophonia, though the evidence base is still developing.
Lip Smacking as Primate Communication
Here is a fact that puts human lip smacking in a fascinating evolutionary context: lip smacking is a major social signal in nonhuman primates. In crested macaques, for instance, lip smacking is used primarily during friendly interactions as an affiliative gesture, essentially the primate equivalent of a warm greeting. A study of these macaques found that lip smacks combining both visual and vocal components (a multimodal signal) increased the likelihood of friendly physical contact, meaning the richer the lip smack, the more effective it was as social communication.17PubMed. Multicomponent and multimodal lipsmacking in crested macaques (Macaca nigra)
Some researchers have proposed that the rhythmic lip-smacking displays in monkeys and apes may be evolutionary precursors to human speech, since both involve rapid, controlled movements of the lips and jaw at similar rhythmic frequencies. Whether or not that theory holds up, it is a useful reminder that our mouths are wired for far more than eating and talking. The motor circuits governing lip movement are ancient, deeply embedded, and tied to social and emotional processing in ways that help explain why lip smacking shows up in such varied contexts, from a baby’s hunger cue to a stress habit to a neurological side effect of medication.
A Practical Checklist for Figuring Out Your Cause
If you are trying to pin down why you or someone you know is smacking their lips, a few questions can help narrow the field:
- Is it voluntary? Can you stop it the moment you notice it, or does it continue even when you try? Voluntary smacking that stops with conscious effort points toward a habit. Involuntary smacking that persists despite effort points toward a neurological or medication-related cause.
- Are you on any medications? Antipsychotics, metoclopramide, and a handful of other drugs are known to cause oral movement disorders. If the smacking started after beginning or increasing a medication, that connection deserves a conversation with your prescriber.
- Are your lips or mouth dry? If the smacking is worst in dry environments, after waking up, or when you are dehydrated, basic moisture management may solve the problem.
- Does it happen during stress or boredom? Habitual lip smacking tied to emotional states responds well to behavioral techniques like habit reversal training.
- Are there episodes of confusion or blank staring? If the smacking comes in discrete episodes with altered awareness, a neurological evaluation is appropriate to rule out seizure activity.
Getting the cause right matters more than jumping straight to a solution, because the wrong intervention wastes time and the right one can make a real difference. A moisturizing lip balm will not fix tardive dyskinesia, and a VMAT2 inhibitor is wildly inappropriate for someone who just needs to drink more water. Start with the cause, and the solution follows.