Spasticity is when your muscles become stiff and hard to move. It can happen to any part of your body, but it most commonly affects your legs. It can range from having a little stiffness to a total inability to stand or walk.

A minor bout of spasticity might involve a feeling of tightness or tension. But severe spasticity can be painful and incapacitating.

Sometimes spasticity involves muscle spasms. A spasm is a sudden, involuntary jerk or muscle movement.

Changing positions or making sudden movements can bring on a spasm. So can extreme temperatures or tight clothing.

About 80 percent of people with multiple sclerosis (MS) have experienced spasticity. For some, it’s an infrequent symptom that passes quickly. For others, it can be unpredictable and painful.

These are the two most common types of spasticity in MS:

Flexor spasticity: This type affects the muscles on the backs of your upper legs (hamstrings) or the top of your upper thighs (hip flexors). It’s an involuntary bending of the knees and hips toward your chest.

Extensor spasticity: This type has to do with the muscles on the front (quadriceps) and inside (adductors) of your upper leg. It keeps your knees and hips straight, but pressed together or even crossed at your ankles.

You can experience one or both types. They’re treated the same way. You can also experience spasticity in your arms, but it’s not as common in people with MS.

If spasticity is becoming a problem, you’ll need to work with your doctor to come up with a treatment plan.

The goal is to relieve symptoms like muscle contractions and pain. Easing symptoms should improve motor skills and your ability to move freely.

Your doctor will probably start out by suggesting simple stretching and other exercises, which may include:

  • yoga
  • progressive muscle relaxation
  • meditation and other relaxation techniques
  • massage

Certain things can trigger symptoms or make them worse. Part of your treatment plan should be identifying triggers so you can avoid them. Some common triggers are:

  • cold temperatures
  • humid conditions
  • tight clothing or shoes
  • poor posture
  • bacterial or viral infection like a cold, flu, bladder infection, or skin sores
  • constipation

Your doctor may refer you to other health professionals like physical or occupational therapists.

Depending on the severity of your symptoms, you can also consider:

  • medications to reduce muscle stiffness
  • orthotic devices, like braces and splints, to help with positioning
  • surgery to sever tendons or nerve roots

Medications can be used to treat MS-related spasticity. The goal of medication is to lessen muscle stiffness without weakening the muscle to the point where you can’t use it.

Whatever medication you choose you’ll probably start with a low dose. It can be gradually increased until you find the dose that works.

Two antispasticity drugs used to treat MS are:

Baclofen (Kemstro): This oral muscle relaxant targets nerves in the spinal cord. Side effects may include drowsiness and muscle weakness. For more severe spasticity, it can be administered using a pump implanted in your back (intrathecal baclofen).

Tizanidine (Zanaflex): This oral medication can relax your muscles. Side effects may include dry mouth, sleepiness, and lower blood pressure. It generally doesn’t cause muscle weakness.

If neither of these medications work, there are some other options. They can be effective, but some side effects can be serious:

  • Diazepam (Valium): It’s not ideal because it can be habit forming and sedating.
  • Dantrolene (Ryanodex): It can cause liver damage and abnormalities in the blood.
  • Phenol: This nerve blocker can cause burning, tingling, or swelling. In rare cases it can cause motor weakness and sensory loss.
  • Botulinum toxin (Botox): This is administered via intramuscular injection. Side effects may include injection site soreness and temporary weakening of the muscle.

Whether you use medication or not, it’s important to incorporate movement into your treatment plan.

Even if you plan to exercise on your own, it might be a good idea to work with a physical therapist first. They can assess your strengths and weaknesses to determine which exercises are most likely to help. Then they can show you how to do these exercises properly.

If you have trouble performing routine tasks like dressing, consider working with an occupational therapist. They can teach you how to use assistive devices and make home modifications to make doing tasks easier.

Learn more: Physical therapy for treating multiple sclerosis »

Braces and splints (orthotic devices) can help keep your legs in proper position so it’s easier to move around. Talk to your doctor or physical therapist before purchasing an orthotic device. If it doesn’t fit well or isn’t well-made, it can make spasticity worse and lead to pressure sores.

Because surgery always carries some risk, it’s usually a last resort. Surgery for spasticity involves cutting tendons or nerve roots to relax stiff muscles. This is generally effective in treating spasticity, but it’s irreversible.

You should mention spasticity or occasional muscle spasms to your neurologist at your next visit, even if it’s not a big problem.

If spasticity is painful or interferes with certain movements, consult with your doctor now.

Without treatment, severe spasticity can lead to:

  • prolonged muscle tightness and pain
  • pressure sores
  • frozen and disabled joints

Early treatment can help you avoid those complications.

Learn more: MS treatments »

Spasticity isn’t always bad. For example, if your leg muscles are so weak that it’s hard to walk, a little spasticity may be helpful. But severe spasticity can interfere with your quality of life.

As with other symptoms of MS, spasticity can vary in degree and frequency. With treatment, you should be able relieve pain and stiffness and improve function.

Work with your doctor to find the right treatment plan and adjust it as your needs change.