When Should I Worry About Leg Cramps? How to Tell If It’s Harmless or a Blood Clot

Leg pain and cramping are common and often result from muscle spasms. While this pain can feel intense, it’s usually not serious. But sometimes what feels like a leg cramp may actually be something more serious: a blood clot in your leg, also called deep vein thrombosis (DVT). 

Here, we’ll review both conditions, provide some clues to help tell the difference, and discuss what to do next.

What are leg cramps?

A leg cramp — sometimes called a “charley horse” — is a painful muscle spasm. It happens when a leg muscle suddenly tightens, usually for a brief period (a few seconds to minutes). This most commonly happens in your calf muscle. But it can also happen in the muscles of your thighs or feet.

Signs that your leg pain may be serious

A leg cramp can be a sign of DVT, which happens when your blood clots inside a vein. DVTs more commonly occur in the smaller veins that travel deep within your lower legs. But they can also occur in other veins throughout your body.

The most common signs and symptoms of a blood clot include:

• Swelling: This may be visible only in your foot or below your knee, or it can affect your whole leg.

• Pain: You may feel cramping, tenderness, or dull pain in your calf, knee, or thigh.

• Redness of the skin: The redness is usually faint and spread out.

• Warmth: The skin over the affected area may feel warmer than the rest of your skin.

Many times, these symptoms only occur in one leg. But sometimes a DVT (or multiple DVTs) can cause symptoms in both legs. Many other conditions, like cellulitis or lymphedema, can also cause these same symptoms. So, DVT can’t be diagnosed by symptoms alone.

It’s also important to note that DVT doesn’t always cause noticeable symptoms, and many people may not know they have one. In fact, up to 40% of people with DVTs may have no symptoms.

When to get care if you are worried about a leg cramp

If you have leg pain that’s worrying you, reach out to a healthcare professional for help, especially if: 

• You have new swelling, redness, or warmth in your leg that wasn’t there before.

• You have risk factors for DVTs or blood clots.

• Your symptoms feel serious or are not going away.

A healthcare professional may order blood tests or do an ultrasound of your veins if they think you may have a DVT. This imaging test can show blood clotting in the veins.

Getting help is important because DVTs can lead to a more serious condition called pulmonary embolism (PE). This happens when parts of the clot break off and travel to your lungs. It can cause symptoms like: 

• Shortness of breath

• Chest pain

• Fainting

• Fast heart rate

• Coughing up blood

PE is a potentially life-threatening condition because it affects your oxygen levels and, in some cases, your blood pressure. If you’re experiencing any of these symptoms, it’s best to see a healthcare professional right away or go to an emergency room to get them checked.

How to tell the difference between leg cramps and a clot (DVT)

Leg cramps and DVTs can feel similar. But there are some differences that can help tell them apart:

• Timing: DVT symptoms are usually subtle at first and then gradually increase over days. Cramps, on the other hand, typically start suddenly, feel intense, and last only seconds to minutes before going away. Cramps also most commonly occur in the middle of the night.

• Swelling: New, one-sided leg swelling is more worrisome for DVT. Leg cramps can result from conditions that cause swelling (like kidney disease), but this swelling is typically there all the time.

• Warmth and redness: DVTs can cause noticeable redness and warmth in your leg, but this is much less common with cramps.

• Risk factors: If you have any of the DVT risk factors mentioned above, a clinician will be more concerned about a blood clot.

Quiz: Do I have DVT?

How do you prevent leg cramps?

If you take medication(s), ask a healthcare professional to review your medication list. They can help you determine if a medication change might help. But don’t stop taking anything before talking with your healthcare team first. 

Here are a few additional steps you can take to help prevent leg cramps:

• Stretch your calf and hamstring muscles frequently and before bed.

• Exercise regularly.

• Stay hydrated.

• Add foods like bananas, pickles, or avocados to your diet.

• Consider wearing compression socks at night.

Contrary to popular belief, magnesium doesn’t seem to help much in terms of preventing muscle cramps.

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Written by:

Nicole Andonian, MD

Nicole Andonian, MD, is a private practice anesthesiologist in Orange County, California. Her focus is in general anesthesia, regional anesthesia, and acute pain management.

Edited by:

Sophie Vergnaud, MD

Sophie Vergnaud, MD, is the Senior Medical Director for GoodRx Health. A pulmonologist and hospitalist, she practiced and taught clinical medicine at hospitals in London for a decade before entering a career in health education and technology.

Reviewed by:

Mandy Armitage, MD

Mandy Armitage, MD, has combined clinical medicine with her passion for education and content development for many years. She is co-executive director at Nonclinical Physicians Network and has served as medical director for the health technology companies HealthLoop (now Get Well) and Doximity.

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