Achy legs have dozens of possible causes, ranging from a long day on your feet to serious circulation problems. The most common culprits are muscle fatigue from overuse, poor blood flow, nerve compression, and mineral deficiencies. Figuring out the cause usually comes down to when the aching happens, where exactly you feel it, and what makes it better or worse.
Muscle Fatigue and Overuse
The simplest explanation is often the right one. Standing or sitting for long stretches puts steady pressure on your leg muscles and blood vessels without giving them a chance to recover. Research on workers who stand for 85% or more of their shifts shows measurable increases in vein size in the lower legs, rising blood pressure, and growing discomfort as the day goes on. Your calf muscles normally act as a pump, squeezing blood back up toward your heart with every step. When you stand still or sit for hours, that pump barely works, and fluid and pressure build up in your lower legs.
Exercise-related soreness is another obvious cause. After a hard workout, a long hike, or even an unusually active day, microscopic damage to muscle fibers triggers inflammation that peaks 24 to 72 hours later. This delayed-onset soreness typically resolves on its own within a few days.
Poor Circulation in the Veins
Chronic venous insufficiency is one of the most underrecognized causes of leg achiness. Inside your leg veins are tiny one-way valves that keep blood flowing upward against gravity. When those valves weaken or fail, blood pools in the lower legs, creating what’s called venous hypertension. The result is that familiar sensation of heavy, aching legs, often with visible swelling by the end of the day.
The pooled blood triggers a chain reaction. Stagnant flow starves nearby tissue of oxygen and creates abnormal pressure on the vein walls. Your body responds by releasing inflammatory signals, including compounds that directly activate pain receptors lining the veins. Those receptors respond to stretching, pressure, and chemical irritation all at once, which is why venous leg pain often feels like a deep, diffuse ache rather than a sharp, localized sting. Symptoms tend to worsen with prolonged standing and improve when you elevate your legs.
Reduced Blood Flow in the Arteries
Peripheral artery disease (PAD) affects an estimated 113 million people worldwide. Fatty deposits narrow the arteries supplying your legs, limiting blood flow, especially during activity. The hallmark symptom is called intermittent claudication: a cramping, aching pain in the calves, thighs, or buttocks that starts when you walk and goes away within a few minutes of rest. Only 10% to 30% of people with PAD experience this classic pattern, though. Many have subtler symptoms like general leg fatigue or no noticeable symptoms at all, which means the condition often goes undiagnosed.
PAD is more common in people over 50, smokers, and those with diabetes or high blood pressure. If your legs consistently ache during walking and feel fine at rest, it’s worth getting checked. A simple, painless test comparing blood pressure at your ankle to your arm can detect the condition.
Nerve Compression and Sciatica
When a herniated disc or bone spur in your lower spine presses on the nerve roots feeding the sciatic nerve, you can feel pain anywhere along the nerve’s path, from your lower back through your buttock and down the back of your leg. The sensation varies widely. Some people describe a sharp, electric jolt. Others feel a dull, persistent ache in the thigh or calf that they might not immediately connect to their back.
Sciatica typically affects one leg at a time. Coughing, sneezing, or sitting for long periods often makes it worse. The aching tends to follow a specific line down the leg rather than spreading evenly across both legs, which helps distinguish it from other causes.
Mineral Deficiencies
Your muscles depend on a careful balance of electrolytes, particularly potassium, magnesium, sodium, and calcium, to contract and relax properly. When these minerals drop too low, the electrical signaling in muscle cells goes haywire. Potassium deficiency, for example, causes at least three problems at once: it reduces blood flow to working muscles, blocks the muscles’ ability to store glycogen (their main fuel), and disrupts normal ion transport across cell membranes. The result can be anything from a vague, persistent ache to full-blown cramping and weakness.
You don’t need to be severely deficient to feel the effects. Dehydration, heavy sweating, certain blood pressure medications, and diets low in fruits and vegetables can all tip the balance enough to cause leg discomfort. If your legs tend to ache and cramp, especially at night or after exercise, electrolyte imbalance is one of the easier causes to address.
Medication Side Effects
Statins, the cholesterol-lowering drugs taken by tens of millions of people, are one of the most common medication-related causes of leg achiness. The pain typically settles in the calves and thighs, though it can be diffuse and affect muscles throughout the body. Observational studies put the rate of muscle complaints at close to 20% of statin users, though the numbers are debated. People with a history of muscle problems, thyroid disorders, or elevated muscle enzymes appear to be more susceptible.
If your leg achiness started after beginning a new medication, it’s worth reviewing the timing with your prescriber. Other drug classes, including certain blood pressure medications and some antibiotics, can also cause muscle pain as a side effect.
Restless Legs Syndrome
Restless legs syndrome produces an uncomfortable sensation deep in the legs, often described as aching, crawling, or throbbing, paired with an overwhelming urge to move. Four features define the condition: the discomfort is accompanied by an urge to move your legs, it starts or worsens during rest, movement partially or fully relieves it, and it’s worse in the evening or nighttime. If all four of those patterns fit your experience, restless legs syndrome is a likely explanation.
The condition is linked to iron metabolism in the brain and often runs in families. It’s more common during pregnancy and in people with iron deficiency. Unlike most other causes of achy legs, restless legs syndrome doesn’t involve visible swelling, skin changes, or pain that worsens with exercise.
Fibromyalgia and Widespread Pain Conditions
When leg achiness is part of a broader pattern of pain in multiple body regions, fibromyalgia may be the underlying cause. The condition involves widespread pain and tenderness lasting at least three months, with no other explanation such as arthritis, infection, or thyroid disease. The aching in fibromyalgia isn’t limited to the legs, but the legs are a common site. Characteristic tender points, specific spots that hurt when pressed, can appear throughout the body.
Fibromyalgia pain is thought to stem from changes in how the nervous system processes pain signals, essentially amplifying sensations that wouldn’t normally register as painful. Fatigue, sleep problems, and difficulty concentrating often accompany the physical symptoms.
When Leg Aching Could Signal a Blood Clot
A deep vein thrombosis (DVT), a blood clot in one of the deep veins of your leg, can produce aching or soreness that starts in the calf and feels like a cramp. What sets it apart from routine achiness: it almost always affects just one leg, and it’s often accompanied by swelling, warmth to the touch, and skin that turns red or purple. Some DVTs cause no obvious symptoms at all.
DVT risk increases after long periods of immobility (a long flight, bed rest after surgery), during pregnancy, and in people taking certain hormonal medications. A clot that breaks free can travel to the lungs, making this the one cause of leg achiness that warrants urgent medical attention if the signs line up.