The involuntary quivering of the lips, known as a perioral tremor, is a common observation in older adults. While this rhythmic shaking is often benign, it may occasionally signal an underlying health issue. The lips and jaw are susceptible to the same involuntary muscle contractions that affect the hands and limbs, which are often amplified with age. Understanding the nature of the tremor is the first step toward determining its cause and appropriate action.
Characterizing the Tremor
A tremor is defined as an involuntary, rhythmic muscle contraction that leads to oscillating movements of one or more body parts. Doctors primarily distinguish between two major types of tremor based on when the movement occurs. This clinical distinction is important because it often points toward different underlying causes.
The first type is a “resting tremor,” which manifests when the muscles are fully relaxed and supported, such as when the mouth is closed. This shaking typically disappears or significantly diminishes when the person actively moves the affected muscles, like when speaking or chewing. The second category is an “action tremor,” which includes quivering that appears or worsens when the person is actively using the muscles.
Action tremors are further divided into postural tremors, occurring when a body part is held against gravity, and kinetic tremors, which happen during voluntary motion. For lip quivering, the context of the movement—at rest versus during activity—is a primary diagnostic tool. The frequency and amplitude of the movement also provide specific clues to the medical evaluation.
Essential Tremor and Parkinsonian Tremor
The two most frequently discussed neurological causes of tremor in older populations are Essential Tremor (ET) and Parkinsonian Tremor. These conditions are differentiated largely by the context in which the tremor presents. Essential Tremor is one of the most common movement disorders and typically manifests as an action or postural tremor.
In individuals with Essential Tremor, lip quivering usually appears when the person is actively using their facial muscles, such as when holding a sustained mouth posture or speaking. While Essential Tremor primarily affects the hands, it can also involve the head, voice, and jaw, often worsening with intentional movement. This progressive neurological condition is characterized by a relatively fast, rhythmic oscillation, often in the 4 to 12 Hertz range.
Conversely, a Parkinsonian Tremor is classically described as a resting tremor. This means the quivering is most noticeable when the lips and jaw are completely relaxed and the person is not performing any voluntary movement. The tremor of Parkinson’s disease is generally slower than an Essential Tremor, typically oscillating at a frequency of 4 to 6 Hertz.
Lip and jaw tremors are observed in a significant minority of people with Parkinson’s disease. This resting tremor often begins on one side of the body before potentially spreading, a characteristic asymmetry that can also be observed in the jaw and lip involvement. The lip quivering associated with Parkinson’s disease may also have a postural component when the mouth is held slightly open, but its primary nature remains at rest.
Secondary Causes and Medication Side Effects
Lip quivering is not always a sign of a progressive neurological condition; it can also be triggered by external factors, systemic issues, or medication side effects. Medication-induced tremor (MIT) is a common cause in older adults, who often take multiple prescriptions. The mechanism is often related to drugs either enhancing a mild, normal physiological tremor or interfering with neurotransmitter systems in the brain.
Several classes of medications are known to cause or exacerbate tremors, including:
- Antidepressants, such as selective serotonin reuptake inhibitors (SSRIs) and tricyclics.
- Mood stabilizers, such as lithium.
- Certain anti-seizure medications.
- Asthma drugs, such as theophylline and albuterol.
The tremor often resolves or improves when the dosage is adjusted or the offending medication is discontinued, though this must only be done under medical supervision.
Beyond medication, various lifestyle and physiological factors can temporarily trigger or worsen perioral quivering. High levels of stress, anxiety, or fatigue can amplify the body’s normal physiological tremor, making it more visible in sensitive areas like the lips. Excessive consumption of stimulants like caffeine, or withdrawal from substances like alcohol, can also cause transient shaking.
Metabolic imbalances, such as an overactive thyroid gland (hyperthyroidism) or low blood sugar (hypoglycemia), can result in a fine, action-based tremor that may affect the facial area.
In some cases, a mild, non-pathological tremor is simply associated with the aging process itself, sometimes referred to as an Aging-Related Tremor (ART). This tremor is often mild and may reflect the general physiological changes in the nervous system that occur with advanced age. These age-related changes are usually benign and do not carry the same implications as the tremors associated with neurodegenerative diseases.
When Professional Consultation is Necessary
While many causes of lip quivering are non-serious, any new or worsening involuntary movement should be evaluated by a healthcare professional. Consulting a doctor allows for an accurate diagnosis, which is the first step toward proper management.
If the lip quivering starts suddenly, begins to interfere with basic activities like eating or speaking, or is accompanied by other neurological symptoms, an evaluation is warranted. Other signs that should prompt a doctor’s visit include the development of stiffness, problems with balance, or slowness of movement in the limbs. These accompanying symptoms may indicate a more complex underlying condition that requires specialized treatment.
A medical evaluation typically involves a detailed history, a physical examination, and tests to rule out metabolic or medication-related causes. Providing a clear description of when the quivering occurs—at rest or during action—will assist the clinician in differentiating between potential diagnoses.