Feeling shaky usually comes down to your nervous system being overstimulated or your body running low on something it needs. The most common causes are low blood sugar, anxiety, too much caffeine, lack of sleep, or a combination of these. In most cases, shakiness is temporary and not dangerous, but persistent or sudden tremors can sometimes point to something that needs medical attention.
Low Blood Sugar Is the Most Common Culprit
When your blood glucose drops below about 70 mg/dL, your body releases stress hormones to force your liver to push more sugar into your bloodstream. Those same hormones cause shakiness, sweating, a racing heart, and irritability. You don’t need to have diabetes for this to happen. Skipping a meal, exercising on an empty stomach, or eating mostly simple carbs that spike and then crash your blood sugar can all trigger it.
If you notice that your shakiness hits a few hours after eating (or after not eating), blood sugar is the likely explanation. Eating something with protein and complex carbs, like peanut butter on whole-grain bread, will usually resolve it within 15 to 20 minutes. If this keeps happening regularly despite eating normally, it’s worth getting your fasting glucose checked.
Anxiety and the Stress Response
Stress hormones like adrenaline act directly on your skeletal muscles. They shorten the active phase of muscle contractions, which means your muscles can’t fully sustain smooth, steady tension. The result is a visible tremor or an internal vibrating feeling, often in your hands, legs, or chest. This is the same mechanism behind shaking before a big presentation or after a near-miss car accident.
The tricky part is that anxiety-related shakiness doesn’t always come with obvious emotional distress. Chronic low-level stress, poor sleep, or even subconscious worry can keep your baseline stress hormones elevated enough to cause intermittent tremors throughout the day. You might feel “wired but tired,” jittery without a clear reason, or notice the shaking gets worse when you’re fatigued or emotionally drained.
Slow, deep breathing (inhaling for four counts, holding for four, exhaling for six) can help dial down the stress response within a few minutes. Pressing your palms together firmly for about 10 seconds and releasing, repeated five times, gives your muscles a controlled contraction that can temporarily reduce tremor intensity.
Caffeine, Stimulants, and Medications
Caffeine is a stimulant that activates the same pathways as adrenaline. Interestingly, research published in Neurology found that a single 325 mg dose of caffeine (roughly three cups of coffee) didn’t reliably increase tremor in formal testing. But individual sensitivity varies widely, and the combination of caffeine with poor sleep, an empty stomach, or background anxiety creates the perfect setup for jitteriness. If you’ve gradually increased your coffee intake or added energy drinks, that’s a good place to start troubleshooting.
A surprisingly long list of medications can also cause tremors as a side effect. Common ones include asthma inhalers (albuterol), antidepressants (SSRIs and tricyclics), mood stabilizers like lithium, some blood pressure medications, steroids, and thyroid hormone replacement if the dose is too high. Nicotine is another frequent offender. If your shakiness started around the same time as a new medication or dosage change, that connection is worth raising with whoever prescribed it.
Electrolyte and Nutrient Gaps
Your muscles depend on a precise balance of minerals to contract and relax normally. Low magnesium is one of the more common deficiencies that causes tremors and muscle spasms. Magnesium deficiency can also drag down your calcium and potassium levels, compounding the problem. You’re more likely to be low if you drink alcohol regularly, take certain medications (especially diuretics or acid reflux drugs), sweat heavily, or eat a diet low in leafy greens, nuts, and whole grains.
Dehydration alone can cause shakiness too, particularly if you’re also low on sodium or potassium from sweating, vomiting, or diarrhea. A blood test can check your electrolyte levels and confirm whether supplementation would help.
Overactive Thyroid
Your thyroid gland controls how fast your metabolism runs. When it produces too much hormone, it’s like your body is stuck in fast-forward. Hyperthyroidism causes a fine tremor, usually most noticeable in the hands and fingers, along with weight loss, a rapid or irregular heartbeat, increased sweating, and feeling hot when others are comfortable. If your shakiness comes with unexplained weight loss or a heart rate that seems higher than usual at rest, a simple blood test for thyroid function can rule this in or out quickly.
Alcohol Withdrawal
If you drink regularly and recently stopped or significantly cut back, shakiness is one of the earliest withdrawal symptoms. Tremors typically begin within 6 to 24 hours after your last drink and tend to peak between 24 and 72 hours. For people with mild to moderate dependence, symptoms usually start improving after that peak. For heavy, long-term drinkers, withdrawal can escalate and become medically serious, so tapering with medical guidance is safer than stopping abruptly.
Essential Tremor and Neurological Causes
Essential tremor is the most common movement disorder, and it’s often confused with Parkinson’s disease, but the two are quite different. Essential tremor shows up when you’re actively using your hands (pouring water, writing, lifting a cup) and primarily affects the hands, head, and voice. Parkinson’s tremor is most visible when your hands are resting in your lap or at your sides, and it often starts on one side of the body. Essential tremor tends to run in families and typically worsens with emotional stress, fatigue, caffeine, or extreme temperatures.
Essential tremor is not dangerous, but it can be frustrating. It often starts mild and progresses slowly over years.
When Shakiness Signals Something Serious
Most shakiness is benign, but certain patterns warrant prompt medical evaluation. Red flags include tremor that starts suddenly (minutes to hours, not gradual), shakiness that appears alongside weakness on one side of the body, difficulty speaking or walking, confusion, or a rapid heart rate with agitation. Tremor that begins before age 50 with no family history of benign tremor also deserves investigation, as it could indicate a structural issue in the brain that imaging can detect.
If your shakiness is new and you can tie it to a missed meal, a stressful week, too much coffee, or a bad night’s sleep, start there. Addressing those basics resolves the vast majority of cases. Shakiness that persists for weeks despite lifestyle changes, gets progressively worse, or interferes with daily tasks like writing or eating points toward a cause worth identifying with your doctor’s help.