Medically reviewed by Debra Rose Wilson, Ph.D., MSN, R.N., IBCLC, AHN-BC, CHT
Written by Zawn Villines
Leg shaking can be a subtle annoyance or an intense experience that causes muscle tension and difficulty walking. Many issues, ranging from restless legs syndrome (RLS) to serious conditions such as dementia, can cause someone’s leg to shake.
It is not possible to diagnose the cause of shaky legs based on symptoms alone. For this reason, people who experience leg shaking should speak to a doctor or healthcare provider.
Keep reading this article to learn about 10 possible causes of leg shaking.
A tremor is an involuntary muscle contraction. The contraction is rhythmic, so a person might feel the muscle shaking or moving at predictable intervals.
A person with a leg tremor may notice their leg shaking while a muscle or group of muscles pulses or spasms out of control. The tremor may last for a few minutes, or it may be an ongoing problem.
Numerous medical conditions can cause a tremor. They are often those that damage the neurological system, including:
- multiple sclerosis
- traumatic brain injury
- brain injuries from tumors
Liver and kidney failure may also cause tremors.
A rare type of tremor, called primary orthostatic tremor, specifically affects the legs. People with this condition notice a sudden tremor upon standing.
This may be a variant of essential tremor, which is a type of genetic tremor, but doctors do not know what causes it. A number of medications may help treat the symptoms.
RLS might look or feel similar to a leg tremor because people with RLS feel an uncontrollable urge to move their legs.
However, a tremor occurs when a muscle spasms out of control. RLS causes voluntary leg movement. These voluntary leg movements occur due to feelings of discomfort. For people with RLS, the legs might tingle, burn, or hurt without movement.
People with RLS often experience symptoms at night, though they can manifest any time.
It is more common among pregnant women, people with nutritional deficiencies, and those with nerve damage due to conditions such as diabetes. That said, anyone can develop RLS.
Doctors do not fully understand the cause, though they suspect that an untreated health condition may have something to do with it. Treating any underlying conditions may help ease RLS.
However, if a doctor cannot find the cause, they may recommend medication to ease the discomfort.
3. Tardive dyskinesia
Certain medications that help treat gastrointestinal and mental health conditions can cause a syndrome called tardive dyskinesia. This involuntary movement disorder causes uncontrolled movements throughout the body, including in the limbs, face, and torso.
More specifically, drugs that change the way the body responds to dopamine — a neurotransmitter that affects movement — can cause tardive dyskinesia.
Antipsychotic drugs, which doctors often prescribe to treat schizophrenia, and the gastrointestinal drugs metoclopramide and prochlorperazine are all common culprits.
People with tardive dyskinesia normally experience other forms of shaking and unusual movements, not just shaking limited to the legs.
Treating tardive dyskinesia usually requires stopping the drug that is causing the issue, and possibly switching to an alternative medication.
Anxiety can temporarily cause shaking, as the body enters a fight-or-flight state. The shaking usually disappears when the anxiety does. However, some people with chronic anxiety may develop tremors that cause chronic bouts of shaking.
Treatment should focus on easing the anxiety, not the tremor, since the anxiety is the cause of the tremor.
Relaxation techniques such as meditation, medication, therapy, and exercising may help.
5. Stimulant drugs
Stimulant drugs can speed up activity in the nervous system. These include prescription medications such as Adderall and Ritalin, as well as illegal drugs including cocaine and methamphetamine.
Use of these drugs may cause shaking or tremors in the legs, hands, or feet. In most cases, symptoms disappear when a person stops using the drug.
A 2012 study, however, suggests that methamphetamine, cocaine, and ecstasy may cause permanent shaking and tremors, especially after prolonged use.
Treatment begins with stopping the drug. If tremors persist, a doctor may recommend medication or physical therapy.
Alcohol misuse and withdrawal can change how the brain and nervous system behave, causing tremors.
Sometimes, the damage will be permanent, such as when alcohol damages the nerves. In other cases, especially when a person is going through alcohol withdrawal, the symptoms are temporary.
People who have misused alcohol for a long time may find relief from tremors by quitting alcohol.
Neuropathy is a type of nerve damage that can cause unusual tingling sensations or pain in the hands and feet. Sometimes, neuropathy extends to the arms or legs, and it may cause shaking or other unusual movements.
Diabetes is one of the most common causes of neuropathy, especially in people with uncontrolled blood glucose. A number of medications may help, and some people may also find relief from massage and other complementary therapies.
The most important treatment for neuropathy is diagnosing and treating the underlying cause. For people with diabetes, neuropathy may be a sign that their current treatment is not working.
Dementia is more than memory loss. It is a type of progressive brain damage that can affect virtually every aspect of a person’s brain function, including movement.
Some people with dementia develop tremors or unusual shaking in their legs or arms. In some cases, these movements may actually be an early symptom of the condition.
There is currently no cure for dementia, but management strategies such as medication and occupational therapy may help with symptoms, including tremors. In some cases, a doctor may prescribe medication to improve mobility.
The thyroid is a gland that plays a role in metabolism, activity level, and other key bodily functions. Hyperthyroidism occurs when the thyroid is too active.
An overactive thyroid causes some processes in the body to speed up. In many cases, an underlying medical condition such as Graves’ disease causes hyperthyroidism.
People with hyperthyroidism may experience muscle spasms, shaking legs or arms, anxiety, restlessness, and unexplained weight loss.
A number of medications, such as beta-blockers and antithyroid medications, may help with the symptoms.
10. Parkinson’s disease
Parkinson’s disease is a condition of the nervous system that affects the brain and nerves. It causes shaking and other uncontrolled movements, and it typically worsens over time.
Many health professionals believe that Parkinson’s causes tremor due to a lack of transmitters in the neurological system.
For some people with Parkinson’s, tremor is the first symptom. In other cases, people with Parkinson’s may develop specific patterns of tremors or shaking, including shaking that affects the legs and undermines mobility.
There is currently no cure for Parkinson’s disease, and the condition tends to get worse with time. However, medication can slow the progression of the condition and restore some mobility.
When to see a doctor
In most cases, a shaking leg is not the result of a serious medical condition. It might instead be due to something such as caffeine withdrawal.
However, if there is no clear cause, if self-care strategies do not work, or if the shaking is getting worse, it is best to see a doctor.
It is especially important to see a doctor if a person experiences other symptoms, including:
- changes in memory or mood
- uncontrolled movements
- mobility problems
- anxiety or restlessness
- trouble sleeping
- wounds on the feet or hands, or other symptoms of uncontrolled diabetes
It can be unpleasant to experience shaking legs, and it might cause a person to worry that something is seriously wrong.
In many cases, the underlying condition is not serious. However, leg shaking can be a symptom of some very serious medical conditions if accompanied by other symptoms. These include Parkinson’s disease, neuropathy, and anxiety.
Delaying treatment allows the problem to get worse. Though shaking legs is not a medical emergency, seeking and receiving prompt medical care can help alleviate this symptom.