What Is Medication-Induced Tremor (MIT)?

Some medications can trigger the onset of a tremor, which are involuntary, unintentional, rhythmic muscle movements.

Tremor occur in the extremities, the trunk and/or the face, voice, head, and are most common in the hands.¹ It is a recognized element of a neurological condition or as a side effect of taking certain medications. Involuntary tremor means you can’t control your shaking.

Tremors can have different causes

It can be challenging to determine the exact cause of tremor, particularly if you already have a neurological condition such as Parkinson’s disease (PD). Uncontrollable tremor is a symptom of PD especially if you are taking multiple medications.² In fact, medications can exacerbate existing tremor or cause non-Parkinson’s tremor.

Medication-induced tremor (MIT) is dependent on a differential diagnosis based on a physical exam and complete medical history.²

Tremor is a recognized symptom of PD and classified as a resting tremor. It is generally moderated when taking standard PD dopaminergic medications. But Parkinson’s is a persistent condition so PD tremor may never go away entirely. It’s common knowledge that Parkinson’s affects each person differently; when, how, and where you experience tremor is unique to you. Parkinson’s tremor is not symmetrical; it disproportionately affects one side of your body.²

What is drug-induced Parkinsonism?

Drug-induced Parkinsonism (DIP) includes resting tremor that is often misdiagnosed as PD. DIP is mostly treated by eliminating the medications that cause the tremor. Sometimes though, people who develop DIP have an underlying dopamine deficiency because of a Parkinsonian syndrome that has not yet been identified.^2,3

What is medication-induced tremor?

There are medical reasons tremor develops. A physical condition like low blood sugar can cause tremor. Starting new medications can cause the initiation of tremor, many of which should resolve, or be less bothersome, as you adjust. Tremor can occur because of drug withdrawal or the dose-response relationship, where increasing the medication dose either worsen the tremor or decreasing the medication resolves it.²

There is not a lot of research that has examined the characteristics of MIT. It can vary in its expression from being a slight inconvenience for some to being disabling for others. Medication-induced tremor is classified as an action tremor; it happens when you try to hold your arms out or other body parts in a particular position.

Unlike Parkinson’s-induced tremor, MIT is generally symmetrical and occurs on both sides of the body. It should disappear over time after you stop taking the medication that’s causing the MIT.²

Risk factors

Risk factors for MIT include older age, taking multiple medications, the existence of other existing medical conditions including mood disorders like anxiety, and depression or chronic pain.

Antidepressants and other common medications can cause tremor.² It is not uncommon for people with Parkinson’s to experience mood disorders. Standard treatment often uses antidepressants or anti-anxiety drugs. These drugs can exacerbate shaking associated with their PD or be the cause of new tremors. Other types of drugs that can also bring on tremor include antipsychotics, anticonvulsants, asthma, and anti-rejection drugs.^2,3

If you are experiencing tremor, make sure to keep a medication record so you can report what you were taking before the tremor began.

Pros & cons to treating MIT

Your doctor can help you determine if the medication regimen is right for you. The doctor is able to evaluate if there are alternative drugs, formulations, or dose adjustments that can help to better manage your medical condition without the presence of tremor.

Some people can eliminate drugs that are inducing tremor. Yet there can be trade-offs between having side effects and benefitting from what could be life-saving treatment with immunosuppressant drugs to prevent transplant rejection.

Make sure to let your doctor know if you are experiencing tremor or other side effects from the medications you take, whether for Parkinson’s or other conditions. Do not stop taking any medications without first discussing what you are experiencing with your medical team.