Living with multiple sclerosis (MS) may mean navigating new or worsening symptoms. Especially during cold and flu season, it can be difficult to tell if you’re dealing with new MS symptoms or influenza (the flu).

Influenza is a contagious viral infection that affects up to 40 million people in the U.S. each year. Multiple sclerosis is an autoimmune disease that causes your body to attack your central nervous system (CNS).

Differentiating between these two conditions can help you get the right care more quickly. Keep reading to learn about five symptoms of MS and the flu that overlap with each other, along with tips for preventing the flu.

1. Fatigue

When you experience extreme physical and mental exhaustion that goes beyond simply being tired, that’s fatigue. About 80 percent of people with MS experience fatigue, and it’s the most commonly reported multiple sclerosis symptom. Among MyMSTeam members, about 59,000 deal with fatigue.

Similarly, influenza causes fatigue that may last for several weeks. If you have the flu, you may feel like you want to sleep all day. When you do get up, you might lack the energy to do anything significant.

It may be hard to differentiate MS fatigue from flu fatigue, but there are differences. MS fatigue typically:

• Happens every day
• Worsens when you’re exposed to heat
• Lasts a long time

If your fatigue is caused by the flu, it may:

• Be accompanied by sore throat, cough, or other flu-related symptoms
• Goes away within a few weeks

If you have MS and the flu or any other upper respiratory infection at the same time, it can compound fatigue. “Been exhausted and sleeping like crazy after a two-week cold,” one MyMSTeam member wrote. If you are experiencing new or worsening fatigue, it is important to consult your physician, who can help you determine between MS progression, medication side effects, other medical conditions, and influenza.

2. Muscle Weakness

MS may cause muscle weakness in some people. The damage that takes place in the CNS prevents nerves from effectively communicating with muscles. This limits your strength and can lead to weak muscles. You may also experience MS muscle weakness if you’re not able to be as active as you used to. The muscles get weaker due to inactivity. Muscle weakness may be worse during an MS relapse (also called an exacerbation or flare-up). Muscle weakness in MS can be highly variable and influenced by many factors. If new or progressive weakness occurs, contact your neurologist.

“My muscles are weakening for sure,” one MyMSTeam member wrote. Another said, “Over the years, I have found that muscle weakness has a greater effect on me when tired. After a nap of 20 to 30 minutes, there is a lot of recovered strength. … This also depends upon how much fuel you have used that particular day.”

In people with the flu, muscle weakness may occur while your body is trying to fight off the infection. As your immune system tries to tackle the virus, inflammation may result, leading to pain and weakness. If your muscle weakness is caused by the flu, it should go away after a few weeks.

3. Dizziness

About 50 percent of people with MS experience dizziness at some point. This may be due to damage that the disease has caused to the central nervous system. If dizziness is related to an MS flare, it may occur alongside symptoms such as balance issues, weakness, or numbness.

“I get dizzy when I look up,” one MyMSTeam member wrote. “I can also get dizzy when I’m just sitting and after I’ve been standing up for a few minutes.”

Among people with the flu, dizziness may occur as a neurological complication. While dizziness can occur with the flu, particularly in severe cases, it is not a typical symptom. If it is accompanied by other neurological symptoms, it can be a serious illness that requires immediate medical attention. If you experience dizziness that doesn’t go away or that happens along with confusion, go to an emergency room for evaluation.

4. Headaches

Headaches aren’t among the most common MS symptoms, but they do occur more often in those with multiple sclerosis than in the general population. In fact, more than 25,000 MyMSTeam members experience headaches. “I have started having daily headaches for weeks,” one MyMSTeam member said. “The last few months, it’s been once a week. They seem to be triggered by tasks requiring processing skills for cognitive tasks.”

Headaches are a frequent occurrence in those who have the flu. They may be mild or severe. Headaches should subside after other flu symptoms stop. If they don’t, it’s important to see a doctor.

While headaches can occur in both MS and the flu, their characteristics may differ. It is important to discuss any new or persistent headaches with your physician to determine the cause and appropriate treatment.

5. Bowel Changes

More than 11,000 MyMSTeam members say that they experience bowel problems. This may come in the form of constipation, diarrhea, or loss of bowel control. Bowel issues are believed to affect about 70 percent of people with MS. “I have chronic diarrhea and it’s taken over my life,” one member wrote. Bowel problems in MS can significantly impact quality of life and require careful management. You should discuss any changes in bowel habits with your doctor.

Some people with the flu may also experience bowel issues. Diarrhea is the most common symptom, though it affects children more than it affects adults. One study of people hospitalized with the flu found that diarrhea was more common in those with influenza B than in those with influenza A. These are two different strains of the flu. A doctor can let you know which strain you have by giving you an influenza test.

MS Treatments and Flu-Like Symptoms

Some multiple sclerosis treatment options may have side effects that mimic the flu. For example, if you’re on an injectable interferon medication, you may experience chills, fever, muscle aches, and joint pain. Interferons include interferon beta-1a (Avonex, Rebif), interferon beta-1b (Betaseron), and peginterferon beta-1a (Plegridy).

If you experience flu-like symptoms while living with MS, talk to your neurology team. It is crucial to never stop or change MS medications without first consulting your neurologist. They can help you evaluate whether your symptoms are related to MS, influenza, your treatments, or another cause.

How Does Flu Affect People With MS?

If you have MS and contract the flu, your symptoms may be more severe than they would be for someone without MS. One study found that people with MS were at an increased risk of hospitalization within the first week after being diagnosed with the flu.

Do People With MS Catch Colds Easier?

People with MS may be more susceptible to catching colds or getting the flu. This can be due to the disease itself, its symptoms, or its treatments.

Some MS treatments may weaken your immune system, leading to a higher risk of getting infections. In addition, infections may be a risk factor that triggers MS flare-ups.

In addition, one study found that any individuals with chronic fatigue issues are more likely to develop infections, such as those from colds and the flu. The combination of diagnoses then worsened overall fatigue, creating a fatigue cycle.

“MS and respiratory issues are a complex duo,” one MyMSTeam member wrote. “I’m exhausted!”

How To Prevent the Flu if You’re Living With MS

During flu season, it’s important to do your best to prevent the flu. It’s also a good idea to wash your hands often and avoid close contact with people who have colds or other upper respiratory infections.

The American Academy of Neurology recommends that people with MS get the annual flu vaccine unless they’re unable to. If you’re taking a disease-modifying therapy (DMT), avoid the live-attenuated virus (such as FluMist nasal spray). Live-attenuated vaccines contain a weakened version of the virus, which can cause a mild form of the disease. This is usually not a problem for people with healthy immune systems, but it can be risky for people taking DMTs, as these medications can weaken their bodies’ ability to respond. Talk to your neurologist or other healthcare provider about whether you should get the flu shot and to evaluate which vaccinations might be right for you.

In addition, if you get the flu and you’re trying to manage it at home, don’t take any supplements or vitamins without talking to your doctor first. Many wellness products could interfere with your MS treatments.

Talk With Others Who Understand

On MyMSTeam, the social network for people with multiple sclerosis and their loved ones, more than 218,000 members come together to ask questions, give advice, and share their stories with others who understand life with multiple sclerosis.

Does MS make you more susceptible to illness? How do you manage multiple sclerosis flu-like symptoms? Share your experience in the comments below, or start a conversation by posting on your Activities page.