Both tremors and dyskinesia are relatively common: About 70 percent of people with Parkinson’s will experience tremors at some time during the course of their disease, according to the Parkinson’s Foundation, and a review published in 2012 in the Journal of Parkinson’s Disease found that about 40 to 50 percent will experience dyskinesia after five years of starting treatment. “People often mix up tremors and dyskinesia because they’re both involuntary extra movements,” says Todd Herrington, MD, PhD, a neurologist at Massachusetts General Hospital and an instructor in neurology at Harvard Medical School. But to better treat these symptoms, it’s important to know how to tell the difference between the two.

What Are Parkinson’s Tremors?

“A tremor is a rhythmic, back-and-forth movement,” says Dr. Herrington. While most tremors tend to occur in the hand, he says that they can also involve other parts of the body, including the thumbs, arms, legs, or head. Tremors also tend to occur when a person isn’t otherwise moving, or is at rest. “We call that a resting tremor,” says Herrington. In such a case, the tremor isn’t as pronounced when the person is using the body part affected by the tremor. However, Herrington says, “when the hand [or other body part] comes to rest . . . the tremor emerges.” Tremors are usually more prominent when Parkinson’s medications are wearing off, he says. During an “off time” — for example, if a person has stopped taking their medicine — they can be slow and stiff or stooped over. “When they walk,” says Herrington, “they’ll take very short steps. They’re moving less, and they’re moving small.”

What Is Dyskinesia in Parkinson’s Disease?

Dyskinesia is predominately a side effect of a medication called levodopa that’s used to treat Parkinson’s disease. “To the trained eye, dyskinesias look quite different [from tremors],” says Herrington. “Dyskinesias are not rhythmic — they have a more writhing quality.” Herrington points out that you can see an example of dyskinesia if you look at videos of Michael J. Fox. “Usually,” he says, “when [Fox] is on camera, he has some dyskinesia, or extra movements that are involuntary.”

Are Tremors or Dyskinesias Painful?

Tremors are almost never painful, says Herrington. And unless the dyskinesias are very severe, they also hardly ever cause pain. However, Herrington says that when a person’s medication wears off, the person can experience a condition called dystonia, which is related to dyskinesia. Dystonia is a potentially painful, cramping condition that can occur in the face, arms, or legs and “can be very uncomfortable.”

How Are Tremors and Dyskinesia Treated?

“We treat these two kinds of movements very differently,” says Herrington. “Dyskinesias are usually a problem of too much dopamine medication [levodopa], and tremors are sometimes a problem of not quite enough. It’s therefore important for a neurologist to be able to tell the difference between the two symptoms, he says, and to adjust the medications accordingly. Herrington points out that not all people are similarly bothered by tremors or dyskinesia. Take tremors, for example. “There are some people who have a very small tremor and it bothers them immensely,” he says. “Other people have quite a substantial tremor and really don’t seem to care about it very much.” When it comes to treating Parkinson’s-related tremors, doctors may start out by asking people how much the symptom bothers them. “As a physician, you can categorize which symptoms people have or the level of severity,” says Herrington, “but it’s always really important to ask the person what bothers them. The most objectively severe symptom may not be the one that bothers them the most.” As for dyskinesia, some people don’t notice it at all, he says. “[With dyskinesia] there is often a divergence between how much they notice and are bothered by it and how much their loved ones notice and are bothered by it.

How Are Tremors and Dyskinesia Experienced by Caregivers?

People with Parkinson’s disease can experience their condition much differently than do their caregivers or spouses. “Sometimes being in the ‘off’ state looks more comfortable to the caregiver because the person is still, and can even seem kind of calm,” says Herrington. “But for the person with Parkinson’s, they experience that ‘off’ state as very uncomfortable. They may describe it as feeling trapped because they want to move but and they can’t. “In this case,” he continues, “the person might say, ‘Look, I know I have dyskinesia, but I prefer being free to move than feeling stuck and trapped.” The caregiver, however, may feel bothered by the increased movement, he says, and think that the person is taking too much medication. “There can be a real disconnect there between what the patient would want and what the caregiver might think is best,” says Herrington. “It’s not always the best thing to try to get rid of every last bit of dyskinesia, because the person might be less comfortable in that state.”

When it comes to managing dyskinesia and tremors, it’s important to strike a balance between too much medication and too little. “You can have too much dopamine medication [levodopa], which can make dyskinesias occur earlier and can make them worse once they start,” says Herrington. “Then there’s the effect of not enough dopamine medication, which can leave people with this ‘off,’ slow, stiff feeling. “The person and the caregiver and loved ones need to be aware of the necessary trade-offs that are involved,” he continues. “Only then can you make an informed decision on how best to move forward.” The more people know about the treatment options for Parkinson’s, the better off they tend to feel. “There may be a situation where a patient feels very uncomfortable in the ‘off’ state but the spouse is bothered by dyskinesias,” Herrington says. “I share with [the spouse] that we can’t necessarily find the perfect dose that gives your partner relief from the slow, stiff, ‘off’ symptoms and causes no dyskinesias. For some patients, finding that middle ground is very difficult.”