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Last reviewed on RxList: 1/22/2021
Lemtrada Side Effects Center

What Is Lemtrada?

Lemtrada (alemtuzumab) is a recombinant humanized IgG1 kappa monoclonal antibody used to treat patients with relapsing forms of multiple sclerosis (MS). Because of its safety profile, the use of Lemtrada should generally be reserved for patients who have had an inadequate response to two or more drugs indicated for the treatment of MS.

What Are Side Effects of Lemtrada?

Common side effects of Lemtrada include:

Dosage for Lemtrada

The recommended dosage of Lemtrada is 12 mg/day administered by intravenous infusion for 2 treatment courses: First Treatment Course: 12 mg/day on 5 consecutive days (60 mg total dose; Second Treatment Course: 12 mg/day on 3 consecutive days (36 mg total dose) administered 12 months after the first treatment course.

What Drugs, Substances, or Supplements Interact with Lemtrada?

Lemtrada may interact with other drugs. Tell your doctor all medications and supplements you use.

Lemtrada During Pregnancy and Breastfeeding

During pregnancy, Lemtrada should be used only if prescribed. It is unknown if this drug passes into breast milk. Consult your doctor before breastfeeding.

Additional Information

Our Lemtrada (alemtuzumab) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


What Is Multiple Sclerosis? MS Symptoms, Causes, Diagnosis See Slideshow
Lemtrada Consumer Information

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Some side effects may occur during the injection or within 24 hours afterward. Tell your caregiver if you feel weak or you have a rash, chest pain, trouble breathing, swelling in your mouth or throat, or fast, slow, or irregular heartbeats.

Lemtrada may cause a serious brain infection that can lead to disability or death. Call your doctor right away if you have problems with speech, thought, vision, or muscle movement. These symptoms may start gradually and get worse quickly.

Lemtrada can cause your immune system to attack cells and organs in your body. This can lead to life-threatening medical problems that may occur up to 3 years after you receive Lemtrada. Call your doctor right away if you have:

  • an overactive immune system--fever, swollen glands, rash, feeling unsteady or less alert, trouble waking, seizure;
  • unusual bleeding--bruising under your skin, nosebleeds, bleeding gums, heavy menstrual periods, bleeding that will not stop, blood in your urine or stools, coughing up blood;
  • kidney problems--swelling in your lower legs, decreased urination, urine that looks pink/brown or foamy; or
  • liver problems--loss of appetite, stomach pain (upper right side), tiredness, dark urine, jaundice (yellowing of the skin or eyes).

Also call your doctor at once if you have:

  • pain or burning when you urinate;
  • a mole that has changed in size or color;
  • pain or swelling in your neck or throat, trouble swallowing or breathing, hoarse voice, or a new cough (not caused by a cold);
  • signs of infection--fever, chills, mouth sores, skin sores, sore throat, cough, pale or yellowed skin, dark colored urine, confusion or weakness, chest pain, fast heartbeats;
  • signs of a stroke or tear in an artery--sudden severe headache, weakness on one side of your body, drooping in your face, neck pain, slurred speech;
  • thyroid problems--sweating, feeling cold, fast heartbeats, feeling nervous or tired, eye swelling, constipation, weight gain or loss;
  • gallbladder problems--fever with nausea, vomiting, and stomach pain;
  • lung problems--cough, wheezing, chest pain, feeling short of breath, coughing up blood;
  • signs of tuberculosis: fever, cough, night sweats, loss of appetite, weight loss, and feeling very tired; or
  • symptoms of herpes virus--cold sores around your mouth, skin sores or blisters, itching, tingling, burning pain in your thigh or lower back.

Common side effects may include:

  • stomach pain, nausea, vomiting, diarrhea;
  • fever, infections;
  • chest pain or tightness, coughing up blood;
  • runny or stuffy nose, mouth or throat pain;
  • rash, itching, tingling, hives;
  • painful urination;
  • headache, dizziness;
  • tiredness, trouble sleeping;
  • joint pain, back pain, pain in your arms or legs;
  • thyroid problems; or
  • flushing (sudden warmth, redness, or tingly feeling).

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Lemtrada (Alemtuzumab Injection for Intravenous Infusion)


What kind of disease is multiple sclerosis? See Answer
Lemtrada Professional Information


The following serious adverse reactions are described below and elsewhere in the labeling:

  • Stroke and Cervicocephalic Arterial Dissection [see WARNINGS AND PRECAUTIONS]
  • Malignancies [see WARNINGS AND PRECAUTIONS]
  • Immune Thrombocytopenia [see WARNINGS AND PRECAUTIONS]
  • Glomerular Nephropathies Including Anti-glomerular Basement Membrane Disease [see WARNINGS AND PRECAUTIONS]
  • Thyroid Disorders [see WARNINGS AND PRECAUTIONS]
  • Other Autoimmune Cytopenias [see WARNINGS AND PRECAUTIONS]
  • Autoimmune Hepatitis [see WARNINGS AND PRECAUTIONS]
  • Hemophagocytic Lymphohistiocytosis [see WARNINGS AND PRECAUTIONS]
  • Acquired Hemophilia A [see WARNINGS AND PRECAUTIONS]
  • Progressive Multifocal Leukoencephalopathy (PML) [see WARNINGS AND PRECAUTIONS]
  • Acute Acalculous Cholecystitis [see WARNINGS AND PRECAUTIONS]
  • Pneumonitis [see WARNINGS AND PRECAUTIONS]

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

In controlled clinical trials (Study 1 and Study 2), a total of 811 patients with relapsing forms of MS received LEMTRADA. The population was 18 to 55 years of age, 65% were female, and 92% were Caucasian. A total of 811 patients received 1 course of therapy, and 789 patients received a second course of therapy at 12 months. The overall follow-up in the controlled trials was equivalent to 1622 patient years.

In MS clinical studies (controlled and open-label extension), overall, a total of 1217 patients received LEMTRADA. Approximately 60% of patients received a total of 2 treatment courses and approximately 24% of patients received a total of 3 treatment courses; others received a total of 4 or more treatment courses, although data beyond 3 treatment courses are limited. The overall follow-up was 6858 person-years. Patients had a median of 6 years of follow-up from the first LEMTRADA dose, with approximately 14% having at least 7 years of follow-up.

Most Common Adverse Reactions

In controlled clinical trials, the most common adverse reactions with LEMTRADA (in at least 10% of patients and more frequently than in interferon beta-1a) were rash, headache, pyrexia, nasopharyngitis, nausea, urinary tract infection, fatigue, insomnia, upper respiratory tract infection, herpes viral infection, urticaria, pruritus, thyroid gland disorders, fungal infection, arthralgia, pain in extremity, back pain, diarrhea, sinusitis, oropharyngeal pain, paresthesia, dizziness, abdominal pain, flushing, and vomiting.

Table 1 lists adverse reactions occurring in ≥5% of LEMTRADA-treated patients in Study 1 and 2 and at the same or at a higher rate than interferon beta-1a.

Table 1: Adverse Reactions in the Pooled 2-Year Active-Controlled Studies in Patients with Relapsing-Remitting Multiple Sclerosis

interferon beta-1a 44 mcg
Urinary tract infection198
Upper respiratory tract infection1613
Herpes viral infection163
Thyroid gland disorders133
Fungal infection134
Pain in extremity129
Back pain128
Oropharyngeal pain115
Abdominal pain105
Blood in urine83
Muscular weakness76
Chest discomfort72
Muscle spasms65
Decrease in CD4 lymphocytes62
Decrease in CD8 lymphocytes62
Decrease in T-lymphocyte count53
Peripheral edema52
Neck pain52
Abnormal uterine bleeding51


Nearly all (99.9%) patients treated with LEMTRADA in MS clinical trials experienced lymphopenia. The lowest lymphocyte counts occurred approximately by 1 month after each course of treatment. The mean lymphocyte count at 1 month after LEMTRADA treatment was 0.25 × 109 L (range 0.02-2.30 × 109 L) and 0.32 (0.02-1.81 × 109 L) for treatment courses 1 and 2, respectively. Total lymphocyte counts increased to reach the lower limit of normal in approximately 40% of patients by 6 months after each LEMTRADA treatment course and approximately 80% of patients by 12 months after each course [see CLINICAL PHARMACOLOGY].

Suicidal Behavior Or Ideation

In clinical studies, 0.6% of patients in both the LEMTRADA and interferon beta-1a groups had events of attempted suicide or suicidal ideation. There were no completed suicides in either clinical study treatment group. Suicidal behavior or ideation occurred in patients with or without a history of a psychiatric or thyroid disorder. Advise patients to report immediately any symptoms of depression or suicidal ideation to the prescribing physician.


As with all therapeutic proteins, there is potential for immunogenicity. The incidence of antibodies is highly dependent on the sensitivity and specificity of the assay. Additionally, the observed incidence of antibody (including inhibitory antibody) positivity in an assay may be influenced by several factors including assay methodology, sample handling, timing of sample collection, concomitant medications, and underlying disease. For these reasons, comparison of the incidence of antibodies to LEMTRADA with the incidence of antibodies to other products may be misleading.

Using an enzyme-linked immunosorbent assay (ELISA) and a competitive binding assay, antialemtuzumab binding antibodies were detected in 62%, 67%, and 29% of LEMTRADA-treated patients, at months 1, 3, and 12 (Course 1) as well as 83%, 83%, and 75% of LEMTRADA-treated patients at months 13, 15, and 24 (Course 2). Samples that tested positive for binding antibodies were further evaluated for evidence of in vitro inhibition using a flow cytometry assay. Neutralizing antibodies were detected in 87%, 46%, and 5% of positive binding antibody patients at months 1, 3, and 12 (Course 1) as well as 94%, 88%, and 42% of positive binding antibody patients at months 13, 15, and 24 (Course 2). Anti-alemtuzumab antibodies were associated with decreased alemtuzumab concentration during Course 2, but not Course 1. Through 2 treatment courses, there was no evidence from clinical trials that the presence of binding or inhibitory anti-alemtuzumab antibodies had a significant effect on clinical outcomes, total lymphocyte count, or adverse events. High titer anti-alemtuzumab antibodies, which were observed in 13 patients, were associated with incomplete lymphocyte depletion following a third or fourth treatment course, but there was no clear effect of anti-alemtuzumab antibodies on the clinical efficacy or safety profile of LEMTRADA.

Postmarketing Experience

The following adverse reactions have been identified during post approval use of alemtuzumab. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Postmarketing Experience With LEMTRADA

Blood and Lymphatic System Disorders: Acquired hemophilia A [see WARNINGS AND PRECAUTIONS], neutropenia, thrombocytopenia [see WARNINGS AND PRECAUTIONS]

Cerebrovascular Disorders: Stroke, including hemorrhagic and ischemic stroke and cervicocephalic arterial dissection [see WARNINGS AND PRECAUTIONS]

Gastrointestinal System Disorders: Cholecystitis, including acalculous cholecystitis and acute acalculous cholecystitis [see WARNINGS AND PRECAUTIONS]

Hepatobiliary Disorders: Autoimmune hepatitis [see WARNINGS AND PRECAUTIONS], viral hepatitis [see WARNINGS AND PRECAUTIONS]

Infections and Infestations: Opportunistic infections [see WARNINGS AND PRECAUTIONS], Progressive multifocal leukoencephalopathy [see WARNINGS AND PRECAUTIONS]

Immune System Disorders: Autoimmune hepatitis, vasculitis, Guillain-Barré syndrome [see WARNINGS AND PRECAUTIONS], hemophagocytic lymphohistiocytosis [see WARNINGS AND PRECAUTIONS]

Pulmonary System Disorders: Pulmonary alveolar hemorrhage [see WARNINGS AND PRECAUTIONS]

Postmarketing Experience With CAMPATH

CAMPATH is approved for the treatment of B-cell chronic lymphocytic leukemia (B-CLL) and is generally administered at higher and more frequent doses (e.g., 30 mg) than recommended in the treatment of MS.

Cardiac Disorders: Congestive heart failure, cardiomyopathy, and decreased ejection fraction in non-MS patients previously treated with potentially cardiotoxic agents.


No information provided.

Read the entire FDA prescribing information for Lemtrada (Alemtuzumab Injection for Intravenous Infusion)

Related Resources for Lemtrada

© Lemtrada Patient Information is supplied by Cerner Multum, Inc. and Lemtrada Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.


What Is Multiple Sclerosis? MS Symptoms, Causes, Diagnosis See Slideshow

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