Muscle Pain: Causes, Types and When to Worry

What muscle pain feels like

Muscle pain can feel like a dull ache, stiffness, a tender knot, a cramp that grips and then lets go, or a sharp, pulling pain with movement. Pain that is in the muscle usually gets worse when you contract or stretch that muscle and is tender when pressed. That helps tell it apart from joint pain, which is felt deep in the joint and with joint movement, and from nerve pain, which burns, tingles or shoots along a line.

Types of muscle pain

Common causes of muscle pain

Overuse, strain and injury

A muscle strain is a stretch or tear of muscle fibers, often in the back, hamstring, calf or neck. Pain starts suddenly during activity, and there may be bruising and swelling. Repetitive work and poor posture cause aching in the neck, shoulders and lower back. Stress makes people hold muscles tight for hours, which leads to tension aches in the neck and upper back.

Delayed-onset muscle soreness

After unfamiliar exercise, small amounts of muscle damage cause soreness that peaks 1 to 3 days later and fades within about a week. It is normal and does not mean you are injured.

Infections

Viral illnesses are a very common cause of widespread aches. Flu classically causes intense aching with fever and exhaustion. COVID-19, colds and many other infections do the same. Lyme disease, from a tick bite, can cause muscle and joint aches with a rash.

Medicines

Statins, used to lower cholesterol, cause muscle aches in some people. Most cases are mild, but a small number develop statin-induced myopathy with raised muscle enzymes. Other medicines that can cause muscle pain include some antibiotics (fluoroquinolones), certain antiretrovirals, and aromatase inhibitors used in breast cancer. Do not stop a prescribed medicine without talking to your doctor.

Cramps and electrolyte problems

Muscle cramps are often linked to fatigue, heat, dehydration, pregnancy, low potassium, magnesium or calcium, and diuretic medicines.

Muscle pain as a symptom of other conditions

Persistent or unexplained muscle pain can be a sign of a wider condition:

• Fibromyalgia: widespread pain for at least 3 months with fatigue, poor sleep and memory problems. Muscle strength and blood tests are normal.
• Polymyalgia rheumatica: pain and stiffness in the shoulders, neck and hips in people over 50, worst in the morning, responding quickly to steroids.
• Underactive thyroid (hypothyroidism): aches, cramps, tiredness, weight gain and feeling cold.
• Myositis: inflammation of the muscles that causes weakness more than pain, sometimes with a rash (dermatomyositis).
• Low vitamin D: vague aching and bone tenderness.
• Chronic fatigue syndrome (ME/CFS): aching that worsens after exertion, with profound tiredness.
• Depression and anxiety: both increase muscle tension and pain sensitivity.

Sudden and severe muscle pain

Most sudden muscle pain is a cramp or a strain. A few causes are dangerous:

• Rhabdomyolysis: muscle breaks down and releases its contents into the blood. Signs are severe pain, weakness, swelling and dark urine. Triggers include extreme exercise (especially in heat), crush injury, long immobility after a fall, some drugs and alcohol. It can damage the kidneys and needs urgent IV fluids.
• Compartment syndrome: swelling inside a closed muscle compartment, usually in the lower leg or forearm after a fracture or crush. Pain is severe, worse on stretching the muscle and out of proportion to the injury. It needs emergency surgery.
• Blood clot: a deep vein thrombosis causes calf pain, swelling, warmth and redness in one leg.
• Poisoning: some toxins and gases cause muscle pain and cramps along with other symptoms such as headache, nausea or confusion. Leave the area and call 911 or your local emergency number, or Poison Control at 1-800-222-1222 in the US.

Muscle pain on the side of the body

Pain in the side muscles, along the ribs and flank, is often a strain of the oblique abdominal muscles or the muscles between the ribs (intercostals). It typically follows twisting, a hard cough, a golf or tennis swing, or lifting. It hurts when you twist, bend sideways, cough or take a deep breath, and one spot is tender to press.

Not all side pain is muscular. Consider other causes when:

• Right side: pain under the right ribs after fatty meals suggests the gallbladder. Pain low on the right with fever and nausea may be appendicitis.
• Either side, toward the back: pain with fever, burning urine or blood in the urine points to the kidney (flank pain).
• Pain worse with breathing and no tender spot: may come from the lining of the lung.
• A band of burning pain on one side, later followed by a blistering rash, is shingles.

See our guide to side pain for a fuller list by location.

When to worry about muscle pain

See a doctor if muscle pain:

• comes with weakness, not just pain
• comes with dark urine, swelling or fever
• lasts longer than 2 weeks, or keeps returning
• started after a new medicine
• affects many muscles and you also feel unwell, tired or are losing weight
• is in the shoulders and hips with morning stiffness and you are over 50

How doctors diagnose the cause of muscle pain

Your doctor will ask where the pain is, how it started, what makes it worse, whether you are weak as well as sore, which medicines you take, and about recent exercise, infections or tick bites. They will check strength, tenderness, joints and skin.

Tests depend on the clues:

• Creatine kinase (CK): a muscle enzyme that rises when muscle is damaged, as in rhabdomyolysis, myositis or statin myopathy.
• Inflammation markers (ESR, CRP): raised in polymyalgia rheumatica and other inflammatory conditions.
• Thyroid function, electrolytes, kidney function and vitamin D.
• Urine test: to look for myoglobin, a muscle protein, in suspected rhabdomyolysis.
• Ultrasound or MRI: for a suspected tear or muscle inflammation.
• EMG and muscle biopsy: for suspected myositis or muscle disease.

Muscle pain treatment and home care

For strains, overuse and soreness:

• Relative rest: reduce, but do not stop, activity. Gentle movement speeds recovery.
• Ice for the first 48 hours after an injury, 15 to 20 minutes at a time wrapped in a cloth. Then heat to relax tight muscles.
• Gentle stretching once the acute pain eases, and a gradual return to activity.
• Pain relief: acetaminophen (paracetamol) or an NSAID such as ibuprofen or naproxen, at the label dose. Avoid NSAIDs if you have kidney disease, stomach ulcers, heart failure or take blood thinners. Topical NSAID gels work well for one sore area with fewer side effects.
• Massage and a foam roller help tension and post-exercise soreness.
• Fluids in hot weather and during long exercise to reduce cramps.

For pain caused by an underlying condition, treatment targets that condition: thyroid hormone for hypothyroidism, steroids for polymyalgia rheumatica, a medicine change for statin myopathy, or exercise, sleep and pain-management programs for fibromyalgia.

Preventing muscle pain

• Increase exercise intensity gradually, by roughly 10 percent a week.
• Warm up before sport and cool down afterward.
• Take breaks from repetitive tasks and set up your workstation to avoid holding awkward postures.
• Lift with your legs, keep loads close to your body, and avoid twisting while lifting.
• Stay hydrated in heat.

Frequently asked questions

What can muscle pain be a symptom of?

Most muscle pain comes from strain, overuse or a viral infection. Ongoing or widespread pain can be a sign of fibromyalgia, polymyalgia rheumatica, an underactive thyroid, low vitamin D, myositis or a side effect of medicines such as statins. Pain with weakness or dark urine needs testing.

When should I worry about muscle pain?

Worry if muscle pain is severe and sudden, comes with dark urine, swelling, weakness or fever, follows a new medicine, or lasts more than 2 weeks. A tense, swollen limb after injury, or muscle pain with a stiff neck and confusion, is an emergency.

Why do my side muscles hurt?

Side muscle pain is usually a strain of the oblique or rib muscles from twisting, lifting, coughing or sport. It hurts with twisting and deep breaths and is tender at one spot. Pain with fever, urinary symptoms or nausea suggests a kidney, gallbladder or bowel cause instead.

Are muscle pains unavoidable?

Some soreness after new or harder exercise is normal and part of how muscles adapt. You can reduce it by building up gradually, warming up and staying hydrated. Persistent or recurring pain without an obvious reason is not something you should simply accept.

How long does muscle pain last?

Exercise soreness lasts 2 to 5 days. A mild strain improves in 1 to 3 weeks, and a moderate strain can take 4 to 8 weeks. Aches from flu fade as the fever settles. Pain lasting longer than expected deserves a check-up.

Should I use heat or ice for muscle pain?

Use ice in the first 48 hours after an injury to limit swelling and pain. After that, or for stiffness and tension that is not from a fresh injury, heat usually feels better and helps the muscle relax.