Everyone feels tired from time to time. But if you have multiple sclerosis (MS), you may experience severe tiredness, sleepiness, or exhaustion, no matter how much sleep you get. This is fatigue, the single most common symptom of MS, which affects between 75 percent and 95 percent of people with the condition.

One possible contributor to fatigue is anemia, which occurs when you have a low concentration of hemoglobin (the part of red blood cells that carries oxygen). Low hemoglobin may be linked to a low red blood cell (RBC) count. Anemia is more common among people living with MS than in the general population and is known to cause or worsen fatigue.

Here’s what you need to know about anemia in MS, why it occurs, and how it can worsen MS-related fatigue.

The Relationship Between Anemia, MS, and Fatigue

The relationship between MS and anemia is unclear. However, the results of a small research study suggest that anemia may be up to twice as likely in people with MS than it is in the general population. The connection might work both ways — people with anemia may be more than twice as likely to eventually develop MS. While these findings would need to be confirmed with further research, they indicate a possible association between MS and anemia.

“I just had a blood test, and they say I’m anemic. How do I get my red blood cells up so I’m not so tired?”

— A MyMSTeam member

According to one study published in Multiple Sclerosis Journal, the association between anemia and MS appears to be higher in men than in women. However, more studies are needed to replicate and confirm these findings.

Although anemia causes significant fatigue, there have not yet been any studies indicating whether and how anemia can contribute to MS-related fatigue. Some researchers believe that fatigue in MS is due to the condition itself and isn’t connected to other conditions, like anemia.

All of this research suggests a connection between MS and anemia, but larger prospective studies are needed to determine the exact nature of the link.

Common Causes of Anemia in MS

Some causes of anemia are linked to MS itself or treatments you may receive for MS. If you have signs of anemia, your doctor can help you find out if it’s linked to MS itself or if it’s a treatment side effect.

MS Treatments and Anemia

Disease-modifying therapies (DMTs) are medications proven to reduce disease activity in MS, lowering the number of relapses and slowing the development of lesions in the central nervous system (brain and spinal cord). Certain DMTs can potentially cause anemia as a side effect. These include:

• Mitoxantrone — Anemia is a known side effect of this medication. It may cause anemia by reducing blood cell production in bone marrow.
• Glatiramer acetate (Copaxone) — Anemia was reported but is uncommon.
• Alemtuzumab (Lemtrada) — Hemolytic anemia was reported in 0.3 percent of study participants with MS treated with this medication.

Rarely, people taking natalizumab (Tysabri), fingolimod (Gilenya) or interferon-beta-1b (Betaseron) have also developed autoimmune hemolytic anemia, in which the immune system destroys RBCs.

Be sure to talk to your neurologist before stopping any medication or making any changes to your MS treatment plan.

Iron Deficiency Anemia and MS Fatigue

You may develop anemia if you have an iron deficiency, which means your body doesn’t have enough iron to make hemoglobin for healthy red blood cells. This can happen if you lose a lot of blood over time or don’t get enough iron through your diet.

Research suggests a possible relationship between MS and iron deficiency. Multiple studies have shown that people with MS commonly have low levels of iron in their blood. Additionally, research shows that iron levels tend to decrease over time in people with progressive MS.

As fatigue is a common symptom of iron deficiency anemia, this might at least partially explain increased fatigue in some people with MS.

Other Causes of Anemia

Anemia may not be a symptom of MS or a side effect of MS treatment. There are three main potential causes of anemia:

• Too little RBC production
• Blood loss
• Too many RBCs being destroyed

Many different health conditions and situations can affect the number of RBCs and cause dysfunction. These can include:

• Not getting enough iron, vitamin B12, or folic acid in your diet
• Having heavy menstrual bleeding (periods)
• Pregnancy
• Blood disorders or other inherited conditions
• Ulcers
• A metabolic disorder called G6PD deficiency
• A condition known as aplastic anemia (which can be inherited or develop later in life)
• Colon cancer or colon polyps

Diagnosing Anemia

Let your doctor know if you’re experiencing significant fatigue beyond what you have come to expect with MS. They may recommend a blood test to screen for anemia. A complete blood count (CBC) will check the numbers of RBCs and measure:

• Hematocrit — The proportion of RBCs in your blood
• Hemoglobin — A protein in RBCs that transports oxygen throughout the body

If either of these are low, your healthcare provider may order further tests to determine the cause of anemia.

Managing Anemia

If you’ve been diagnosed with anemia, talk to your neurologist about how best to manage it. Treating your anemia may help alleviate some of your fatigue, improving your overall well-being and quality of life.

There are several treatments or interventions available for anemia. Recommendations will depend on what is causing your anemia.

Anemia caused by an iron deficiency can be managed by taking iron supplements or incorporating more iron-rich foods into your diet. Other vitamins, like B12, can also be taken through oral supplements, injections, or intravenous infusions.

Some types of anemia require a blood transfusion or a bone marrow transplant, although these are less common. Certain medications can be prescribed to help your body produce more RBCs.

As always, talk to your doctor before starting any new supplements, even if they’re available over the counter. Your doctor will be able to recommend the right dosage for you and determine whether any supplements may potentially affect your MS or its treatment.