Medication Search: Lemtrada

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How does this medication work? What will it do for me?

Alemtuzumab belongs to the class of medications called selective immunomodulators. It is used to treat adults with relapsing remitting multiple sclerosis (RRMS) with highly active disease and for whom other treatments have not been effective or not tolerated.

MS is a disease that affects the nervous system. It is believed that MS is an autoimmune disease (a condition in which an individual’s immune system starts reacting against their own tissues) and cannot be spread from person to person. For unknown reasons, the immune system sees the myelin sheath (a protective layer covering the nerves) as foreign and attacks it.

Alemtuzumab appears to affect the immune system to reduce the activity of the immune system attacking the myelin sheath, slowing down damage to the nerves.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Each mL of clear, colourless to slightly yellow, preservative-free concentrate solution that must be diluted before IV infusion contains 10 mg of alemtuzumab. Nonmedicinal ingredients: sodium chloride, dibasic sodium phosphate, potassium chloride, potassium dihydrogen phosphate, polysorbate 80, disodium edetate dehydrate, and water for injection.

How should I use this medication?

Alemtuzumab is generally given as 2 treatment courses. The first treatment course of alemtuzumab is 12 mg given as a single intravenous infusion (into the vein) once a day for 5 days. This medication is given over approximately 4 hours.

The second treatment course is given 12 months after the first course. A single daily infusion of 12 mg of alemtuzumab is given over 4 hours each day for 3 days.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

Careful handling of this medication is required. It is always given under the supervision of a doctor in a hospital or similar setting with access to sterile equipment for preparation.

Your doctor will want you to stay at the hospital or clinic where you receive your doses of alemtuzumab for at least 2 hours after the infusion is finished. This allows the medical team to be available to treat any serious infusion-related reactions that may occur shortly after you receive the dose of medication.

It is important this medication be given exactly as recommended by your doctor. If you miss an appointment to receive alemtuzumab, contact your doctor as soon as possible to reschedule your appointment.

This medication will be stored under refrigeration by the pharmacy or clinic where you receive the infusion.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take alemtuzumab if you:

  • are allergic to alemtuzumab or any ingredients of the medication
  • are infected with Human Immunodeficiency Virus (HIV)
  • have or have had tuberculosis
  • currently have any severe infection
  • have active cancer
  • are taking medications to treat cancer or medications that weaken your immune system
  • have a history of progressive multifocal leukoencephalopathy (PML)
  • have high blood pressure that is not controlled
  • have a history of stroke or arterial dissection
  • have a history of angina or heart attack
  • have a clotting disorder or are taking anticoagulants

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • abdominal pain
  • acne
  • altered sense of taste
  • constipation
  • back, joint, or arm/leg pain
  • decreased appetite
  • diarrhea
  • dizziness
  • dry mouth
  • hair loss
  • headache
  • heartburn
  • hiccups
  • hives
  • itching
  • loss of balance
  • nausea
  • night sweats
  • skin redness or discolouration
  • spinning sensation
  • trouble sleeping
  • vomiting
  • weakness
  • weight changes

Although most of the side effects listed below don’t happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • anxiety
  • blisters
  • blurred or double vision
  • difficulty swallowing
  • fast or irregular heartbeat
  • fever
  • flu-like symptoms (sudden lack of energy, fever, cough, sore throat)
  • increased blood pressure
  • inflammation of the gallbladder (e.g., stomach pain or discomfort, fever, nausea or vomiting)
  • irregular or heavy menstrual periods
  • lung problems (e.g., shortness of breath, cough, wheezing, chest pain or tightness, coughing or spitting up blood)
  • mouth pain or inflammation
  • muscle pain or weakness
  • nervousness
  • numbness or tingling; burning or prickling sensation
  • rash
  • signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don’t stop bleeding)
  • signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
  • signs of kidney problems (e.g., increased urination at night, decreased urine production, blood in the urine, swelling in the feet and legs)
  • signs of liver damage (e.g., nausea, vomiting, abdominal pain, fatigue, loss of appetite, yellowing of the skin or eyes, dark urine)
  • signs of decreased thyroid function (e.g., dry skin, constipation, weight gain, fatigue, aches, pains and stiffness, intolerance to cold, depression, memory problems)
  • signs of yeast infections (e.g., athlete’s foot, oral thrush, vaginal thrush)
  • skin colour changes
  • sore throat
  • symptoms of autoimmune disorders (e.g., seizures, movement changes, behaviour changes, confusion, skin rash, fever, fatigue, muscle weakness)
  • symptoms of infection (e.g., fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, listlessness, cold sores, or shingles)
  • symptoms of overactive thyroid (e.g., anxiety or nervousness; weight loss; frequent and loose bowel movements; breathlessness; feeling hot; feeling of having rapid, fluttering, or pounding heart)

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • signs of heart attack (e.g., sudden chest pain or pain radiating to back, down arm, or jaw; feeling of fullness of the chest; nausea; vomiting; sweating; or anxiety)
  • signs of stroke (e.g., sudden or severe headache, sudden loss of coordination, vision changes, sudden slurring of speech, or unexplained weakness, numbness, or pain in arm or leg)
  • symptoms of an infusion reaction (e.g., changes in heart rate, headache, rash, feeling tired, nausea, fever, hives, chills, or reddening of the face and neck)
  • signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.


October 15, 2019

Health Canada has issued information concerning the use of alemtuzumab. To read the full Health Canada Advisory, visit Health Canada’s web site at

Autoimmune conditions: Rarely, alemtuzumab, like other similar medications, can cause other serious, possibly fatal autoimmune conditions. Your doctor will order blood tests to monitor for changes that could signal the development of one of these conditions. If you experience any unusual or unexpected effects, contact your doctor to have these effects checked out.

Bleeding: Alemtuzumab may cause a reduced number of platelets in the blood, which can make it difficult to stop cuts from bleeding. If you notice any signs of bleeding, such as frequent nosebleeds, unexplained bruising, or black and tarry stools, notify your doctor as soon as possible. Your doctor will order routine blood tests to make sure potential problems are caught early.

Immune system and infections: Alemtuzumab may lower your ability to fight infections and may increase the risk of infections and reactivate inactive infections. Your doctor may test for tuberculosis before starting this medication.

Your doctor will do regular tests of immune system function while you are using this medication. If you develop a severe infection, contact your doctor as soon as possible.

Infusion reactions: Alemtuzumab may cause side effects while the medication is being given, and for a period of time afterwards. If you experience headache, rash, fever, itchiness, chills, flushing, chest pain or discomfort or dizziness, let your doctor know immediately. Your doctor may give you medications to help prevent these effects.

Kidney function: Alemtuzumab may decrease kidney function. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: Rarely, this medication may cause severe and possibly life-threatening liver problems. If you experience signs of decreased liver function, such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Malignancies (cancer): Alemtuzumab may increase the risk of developing cancer including thyroid cancer, certain types of lymphoma, and skin cancer. Discuss any concerns you have with your doctor.

Progressive multifocal leukoencephalopathy (PML): There have been reports of PML after using alemtuzumab. PML is a rare disorder that causes nerve damage in the brain. If you experience memory loss, vision loss, trouble thinking, or difficulty walking, contact your doctor immediately.

Serious infections: Alemtuzumab can affect the way your body’s natural defenses work to fight infection. This makes the body more likely to develop infections due to bacteria, viruses, and fungi. This effect is increased if you are taking alemtuzumab with other medications that reduce the body’s ability to fight infection. For some people, these infections have been fatal. If you have a history of chronic or frequent infections, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Stop taking the medication and tell your doctor right away if you notice symptoms of a serious infection, such as fever, chills, headache, flu-like symptoms, feeling tired, cough, blood in the sputum, shortness of breath, night sweats, weight loss, nausea, vomiting, diarrhea, frequency or burning while passing urine, redness or swelling of skin or joint, cold sores, tooth pain, or new or worsening pain in any part of the body.

Stroke and heart attack: There have been reports of people experiencing a stroke, heart attack, or other serious reactions including bleeding in the lung or tears in blood vessels supplying the brain after receiving an infusion of alemtuzumab. Stroke symptoms may include confusion, sudden or severe headache, sudden loss of coordination, vision changes, sudden slurring of speech, or unexplained weakness, numbness, or pain in arm or leg. Heart attack symptoms may include sudden chest pain or pain radiating to back, down arm, or jaw; a sensation of fullness of the chest; nausea; vomiting; sweating; or anxiety. If you experience any of these symptoms, get immediate medical attention.

Thyroid problems: Some people taking this medication develop changes in the function of their thyroid. Symptoms of these changes include feeling cold or hot all the time, a change in weight (gain or loss) without a change in your diet or amount of exercise you get, or feeling emotional. Contact your doctor if you experience these symptoms.

Vaccinations: It is not known how effective vaccines may be after treatment with this medication. Certain immunizations may be dangerous if given while receiving or shortly after receiving a treatment course of alemtuzumab. Before starting treatment with this medication, check with your doctor to ensure your immunizations are up to date. Vaccinations should be complete at least 6 weeks before starting alemtuzumab.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Those who may become pregnant should use effective birth control when receiving alemtuzumab and for at least 4 months after the course of treatment.

Breast-feeding: It is not known if alemtuzumab passes into breast milk. If you are breast-feeding and taking this medication, it may affect your baby. People should not breast feed for at least 4 months after the last infusion of a treatment course. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

What other drugs could interact with this medication?

There may be an interaction between alemtuzumab and any of the following:

  • 5-ASA medications (e.g., mesalamine, olsalazine, sulfasalazine)
  • abrocitinib
  • apixaban
  • baricitinib
  • BCG
  • cladribine
  • clozapine
  • dabigatran
  • deferiprone
  • deucravacitinib
  • edoxaban
  • heparin
  • leflunomide
  • low molecular weight heparins (e.g., dalteparin, enoxaparin, tinzaparin)
  • natalizumab
  • nivolumab
  • ocrelizumab
  • ofatumumab
  • olaparib
  • pimecrolimus
  • promazine
  • rivaroxaban
  • ruxolitinib
  • sphingosine 1-phosphate (S1P) receptor inhibitors (e.g., fingolimod, ponesimod, siponimod)
  • tacrolimus
  • tofacitinib
  • upadacitinib
  • vaccines
  • warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

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Last Updated: 16/07/2024