When a person with relapsing-remitting multiple sclerosis (MS) has an acute symptom flare-up, they are often prescribed a short course of high-dose steroids, according to the National Multiple Sclerosis Society (NMSS). Typically, steroids are given intravenously or orally for three to five days.

“High-dose steroids are used to speed recovery” after an MS relapse, says Matthew McCoyd, MD, an associate professor and residency program director of neurology at the Loyola University Medical Center in Maywood, Illinois.

The steroids used for MS flares are known as corticosteroids, which mimic natural hormones produced in the adrenal gland and which interrupt inflammation.

"Because of long-term complications, like bruising, skin changes, and bone changes, we only use them for short periods, and it is rare to use them more than once or twice a year," Dr. McCoyd says.

But even in the short term, steroids can have side effects — although, says McCoyd, once you start to taper the drug, most side effects will subside.

“In general, steroids are very well tolerated,” says Tamara B. Kaplan, MD, a clinician at Brigham Multiple Sclerosis Center at Brigham and Women’s Hospital in Boston. “And these side effects should never deter you from getting proper treatment.”

However, it helps to know what you may be in for, so here are six possible side effects to be aware of:

1. Sleep Problems Common From High-Dose Steroids

“One of the most common side effects from the initial high dose of steroids is sleep disturbance,” McCoyd says.

Steroids can give you an extra boost of energy, explains Dr. Kaplan. She advises her patients to schedule their infusions for early in the day so they don’t interfere with sleep.

If you do have trouble falling asleep, experience unpleasant dreams, or feel sleepy or fatigued during the day, the following tips may help:

Take the steroids early in the morning, and avoid afternoon or evening dosing.
Ask your doctor for prescription sleep medication.
If you also take drugs with sedating effects, such as antidepressants, take them at bedtime.

2. Bad Taste, Upset Stomach a Possibility

Some people notice a funny, metallic taste in their mouth when undergoing steroid treatment. Sucking on mints or hard candies may help alleviate it.

Other common side effects of steroids include upset stomach, nausea, and vomiting. If you experience indigestion or heartburn, ask your doctor to suggest an over-the-counter antacid to help control it.

Medications called proton pump inhibitors, such as Prilosec (omeprazole) or Prevacid (lansoprazole), are also used to help with stomach symptoms, and your doctor may prescribe them to prevent stomach issues, says Barbara Giesser, MD, a multiple sclerosis specialist with Pacific Neuroscience Institute in Santa Monica, California, and professor emeritus of clinical neurology at the David Geffen UCLA School of Medicine in Los Angeles.

3. Mood Disturbances: Agitation, Irritability, Mood Swings

Being on a steroid can make you feel restless, agitated, and irritable.

“Agitation is a common symptom for some people," McCoyd says. In addition, “Patients who have a mood disorder may be treated in the hospital to make sure they do not have a serious bout of depression or anxiety.”

Mood swings with steroid treatment can range from mild to serious. Be sure to tell your doctor if you have a history of depression, anxiety disorder, or bipolar disorder.

Simply being aware that steroids can affect your moods may make this side effect easier to tolerate, but let your doctor know if it feels intolerable.

It’s also important to let loved ones know about this possible side effect so they understand what’s going on with you. “I always warn the partner: ‘She might be a little more irritable over the next few days. It’s the medicine; it’s not her,’” notes Kaplan.

4. Water Retention Annoying but Temporary

After the initial dose of steroids, you may experience swollen ankles as well as a general swollen and bloated feeling throughout your body. Since steroids cause your body to retain more water, it’s also common to experience urinary frequency, says Kaplan.

Just knowing that this can potentially happen — and that it will soon pass — can help.

“It’s not something to worry about,” she says. “It’s not a long-lasting symptom; it will improve within a few days.”

5. Infection Risk Rises With Steroid Use

One of the functions of a steroid is to suppress your body’s immune system, which places you at higher risk of infections.

If you develop any symptoms of infection while taking a steroid — such as a fever, chills, cough, or sore throat — let your doctor know, says McCoyd.

You can lower your risk of infection with frequent hand-washing and by keeping your distance from people with cold or flu symptoms.

While people with MS are generally encouraged to get an annual (non-live) flu vaccine, as well as certain other vaccines, the NMSS cautions against getting any vaccines during an MS relapse — whether or not you’re taking steroids. Also, live and live-attenuated vaccines are not recommended for people who have MS who are taking any disease-modifying therapy (DMT). There are also some restrictions on receiving some non-live vaccines if you are taking certain medications for MS.

6. Elevated Blood Sugar a Concern for Those With Diabetes

One of the most important side effects of steroids is high blood sugar levels. This is usually not a problem unless you have diabetes, but if you do have diabetes, you are likely to see higher numbers when you check your blood glucose level.

“People with diabetes should be warned that their blood sugar will go up and that they need to talk to their doctor about adjusting their insulin [or other diabetes medication] while they are on the steroid,” says Kaplan.

People without diabetes sometimes develop steroid-induced diabetes during steroid treatment. If you notice unusual thirst, dry mouth, frequent urination, blurred vision, or extreme weakness and fatigue while on steroids, let your doctor know.

Alternatives to Steroid Treatment

When someone cannot tolerate steroids or does not adequately respond to steroid treatment, the following alternatives may be considered, according to the NMSS:

Acthar Gel Acthar Gel stimulates the outer layer of cells of the adrenal gland, which helps your body produce natural hormones that reduce inflammation, according to the Multiple Sclerosis Association of America. It contains a highly purified preparation of the hormone adrenocorticotropin (ACTH) in gelatin, which is injected either into the muscle or under the skin. Commonly reported side effects include injection site reaction, fatigue, fluid retention, insomnia, headache, and high blood sugar.
Plasmapheresis Also known as plasma exchange, this treatment may be used to treat severe flares.

Additional reported by Susan Jara.

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