Most calf pain comes from the calf muscles or the Achilles tendon. But calf pain can also come from
a blood clot in a deep leg vein, from reduced blood flow to the leg, or from an irritated nerve in
the lower back. The pattern usually separates them, and one of them, a clot, needs same-day
assessment.

Could my calf pain be a blood clot?

This is the first question to answer, because a deep vein thrombosis (DVT, a blood clot in one of
the deep veins of the leg) is a real and reasonably common cause of calf pain.

The typical picture is pain or a deep cramping ache in one calf, not both. That leg often swells,
and the calf can look visibly larger than the other. It may feel warm, the skin can look red or
change colour, and pressing along the deep part of the calf is tender.

Some situations raise the risk: recent surgery, a long flight or drive, a spell of immobility, a
cast, pregnancy or recent birth, cancer, some hormonal medication, and a previous clot.

If this sounds like your calf, you need a same-day medical assessment. A clot cannot be ruled out at
home, and no online article can rule it out for you. It takes an examination plus a blood
test or an ultrasound scan.

If calf pain comes with chest pain, breathlessness, or coughing up blood, treat it as an emergency
and call 911. Those can be signs that a clot has travelled to the lungs, which is life threatening.

What muscle problems cause calf pain?

A calf strain is the most common cause. It usually happens mid-activity: a sudden sharp pain at the
back of the lower leg, often described as feeling like being struck from behind.

Delayed soreness is different: it builds over the day or two after unaccustomed exercise, affects
both calves, and fades over several days.

Cramp is a sudden involuntary tightening that grips the muscle and then releases. It can happen
during activity or at rest, including in bed. Tight calf muscles also pull on the heel, which is why calf
tightness and heel pain often appear together.

Can the Achilles tendon cause calf pain?

Yes. Achilles tendinopathy (irritation of the thick tendon joining the calf muscles to the heel
bone) causes pain and stiffness low at the back of the leg and into the heel. The clue is timing:
worst on the first steps of the morning and at the start of activity, easing as the tendon warms
up.

Can a nerve in my back cause calf pain?

Yes, and it surprises people. An irritated nerve root in the lower back can send pain into the calf
with no back pain at all. The clue is the quality. Nerve pain tends to be burning, electric, or
shooting rather than aching, and often comes with pins and needles into the foot. Our page on
back pain and lumbar radiculopathy
explains how a lower back nerve refers pain down the leg, and our post on
what sciatica feels like
describes the sensation.

Can poor circulation cause calf pain?

Yes, and this pattern is the most useful one to recognise. Peripheral arterial disease
(narrowed leg arteries that limit blood flow to the muscle) produces calf cramping that
starts reliably after walking a set distance. It eases within a few minutes of standing still, then
returns at roughly the same distance next time.

That reproducibility is the giveaway. A strain does not behave like a stopwatch. This pattern
deserves a doctor’s assessment, because leg circulation reflects heart and vascular health more
broadly.

What else causes calf pain?

Three less common causes:

• A popliteal cyst (a Baker’s cyst), a fluid-filled swelling behind the knee, can leak downward and
  cause calf pain and swelling.
• Compartment syndrome, a build-up of pressure inside a muscle compartment, causes exercise-related
  calf tightness and pain in athletes.
• Statins, taken for cholesterol, cause muscle aching in some people, usually in both legs.

Calf pain patterns and what they usually mean

• One calf swollen, warm, and tender: possible blood clot, same-day assessment.
• Sudden sharp pain during a sprint or a jump: calf strain.
• Cramping after a set walking distance, easing with rest: circulation, possibly peripheral
  arterial disease.
• Stiffness and pain worst in the first steps of the morning: Achilles tendinopathy.
• Burning or electric pain with pins and needles: nerve, often from the lower back.
• Both calves aching a day after new exercise: delayed muscle soreness.
• Sudden gripping tightness at night that releases: night cramp.

Why does calf pain happen at night?

Night cramps are common and usually harmless, though intensely painful for a minute or two. Gently
stretching the calf often settles them.

One night pattern matters more. Pain that is constant, does not change with position, and keeps you
awake is a different picture, and should be assessed rather than waited out.

What helps calf pain?

For muscular causes, the principle is relative rest rather than complete rest. Easing off briefly,
then returning to load gradually, works better than stopping altogether: muscle and tendon need
load to recover. Progressive calf strengthening is the mainstay. Footwear and training load are
worth reviewing, since most strains follow a jump in volume or a change of surface.

For nerve-driven calf pain, the target is the source in the back, not the calf itself.

An interventional pain clinic starts with assessment to identify where the pain is coming from. Where a lower back nerve root is the source,
nerve blocks and nerve root injections placed precisely
using imaging can be used to calm the irritated nerve. Where pain has become persistent and
neuropathic (generated by the nerve itself), the options we use for
peripheral neuropathy apply. Many patients
find a clear diagnosis is the part that changes their plan.

Warning signs: when calf pain needs urgent care

Seek same-day or emergency care if you have:

• One calf that is swollen, warm, and tender: possible clot, same-day assessment.
• Calf pain with chest pain, breathlessness, or coughing up blood: emergency, call 911.
• A cold, pale, or blue foot with severe pain: emergency.
• A sudden pop at the back of the leg with an inability to push off.
• A hot, red, swollen calf with a fever.
• Severe, tight, painful swelling after exercise or injury that keeps getting worse.
• New weakness in the leg, or a foot that drops.

Frequently asked questions

When should I worry about calf pain?

Worry when one calf is swollen, warm, and tender, because that can mean a blood clot and needs
same-day assessment. Treat calf pain with chest pain or breathlessness as an emergency. Also get
checked if pain is constant at night, starts after a set walking distance, or comes with new
weakness.

How do I tell a calf strain from a blood clot?

A strain usually starts at a clear moment during activity, with sharp pain you can point to, and
eases over days. A clot tends to build over hours or days with no obvious trigger, with swelling of
the leg, warmth, and a calf larger than the other. If unsure, get assessed the same day.

Why do I get calf pain at night?

Night cramps are the usual reason: a sudden gripping tightness that releases after a minute or two.
They are common and generally harmless. Pain at night that is constant, unaffected by how you lie,
and not eased by stretching is a different pattern, and worth having a doctor look at.

Do I need an ultrasound for calf pain?

Not for most calf pain. A strain, a cramp, or an Achilles problem is usually identified from your
history and an examination. An ultrasound is the usual test when a blood clot is suspected, and that
decision belongs to a doctor who has examined the leg.

This article is general information, not medical advice. It cannot diagnose your pain. If your
symptoms are new, worsening, or worrying you, speak with your family doctor or contact us for an
assessment.

Getting your calf pain assessed

If calf pain has lasted weeks, keeps returning, or carries the burning, electric quality of nerve
pain, an assessment can identify where it is coming from. Our physicians at Silver Pain Centre in
North Toronto assess and treat nerve-driven leg pain, and most services are covered by OHIP with a
physician referral. Ask your family doctor to send a
physician referral, or start a
self-referral yourself.