Reviewed on 10/13/2022

What Is Alemtuzumab and How Does It Work?

Alemtuzumab is a prescription medication used for the treatment of chronic lymphocytic leukemia and multiple sclerosis.

What Are Side Effects Associated with Using Alemtuzumab?

Common side effects of Alemtuzumab include:

  • nervousness,
  • burping,
  • bone pain,
  • numbness or tingling,
  • burning, crawling, or itching of the skin,
  • heartburn,
  • indigestion,
  • weakness,
  • stomach pain,
  • swelling or inflammation of the mouth,
  • weight loss,
  • constipation,
  • sensitivity to hot or cold temperatures,
  • drowsiness, and
  • stuffy nose

Serious side effects of Alemtuzumab include:

  • hives,
  • difficulty breathing,
  • swelling of the face, lips, tongue, or throat,
  • excessive sweating,
  • eye swelling,
  • unexplained weight loss,
  • nervousness,
  • unexplained weight gain,
  • worsening tiredness,
  • feeling cold,
  • constipation,
  • black, tarry stools,
  • blood in the urine,
  • chills,
  • cough,
  • diarrhea,
  • dizziness,
  • fainting,
  • lightheadedness,
  • fast, irregular or pounding heartbeat,
  • fever,
  • headache,
  • itching,
  • skin rash,
  • nausea,
  • painful or difficult urination,
  • chest pain or pressure,
  • hoarseness,
  • low back or side pain,
  • pale skin,
  • sore throat,
  • sores or ulcers on the lips or in the mouth,
  • sweating,
  • swollen glands,
  • tightness in the chest,
  • unusual bleeding,
  • easy bruising,
  • tiredness,
  • weakness,
  • vomiting,
  • cold sores or blisters on the lips, nose, eyes, or genitals,
  • rapid weight gain,
  • tremor,
  • red or purple spots on the skin,
  • flushing of the face or neck,
  • anxiety,
  • back pain,
  • joint pain, stiffness, or swelling,
  • lack of appetite,
  • light-colored stools,
  • blurred or double vision,
  • confusion,
  • dark urine,
  • little or no urination,
  • vision loss,
  • drowsiness,
  • muscle aches or pain,
  • nightmares or unusually vivid dreams,
  • numbness, pain, tingling, or weakness,
  • pain or discomfort in the arms, jaw, back, or neck,
  • painful or tender lymph glands in the neck, armpit, or groin,
  • seizures,
  • shakiness and unsteady walk,
  • difficulty in speaking or slow speech,
  • spitting or coughing up blood,
  • dilated neck veins,
  • eye pain,
  • extreme tiredness,
  • feeling unwell,
  • depression or sadness,
  • difficulty to move the arms, legs, or facial muscles,
  • inability to speak,
  • irregular breathing,
  • irritableness,
  • yellowing of the skin or eyes (jaundice),
  • upper right abdominal pain,
  • a feeling of fullness,
  • unsteadiness or poor coordination,
  • trembling,
  • difficulty sleeping, and
  • trouble concentrating

Rare side effects of Alemtuzumab include:

  • none

Seek medical care or call 911 at once if you have the following serious side effects:

  • Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors;
  • Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
  • Serious heart symptoms include fast, irregular, or pounding heartbeats; fluttering in the chest; shortness of breath; sudden dizziness, lightheadedness, or passing out.

This is not a complete list of side effects and other serious side effects or health problems that may occur because of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.


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What Are Dosages of Alemtuzumab?

Adult dosage

Injectable solution

  • 10 mg/mL (Lemtrada; 1.2 mL/vial [12 mg/1.2 mL])
  • 30 mg/mL (Campath; 1 mL/vial)

Chronic Lymphocytic Leukemia (Campath)

Adult dosage

  • Administer 3 mg IV every day until infusion reactions are Grade less than 2, THEN
  • Administer 10 mg IV every day until infusion reactions are Grade less than 2, THEN
  • Administer 30 mg IV 3x/week (on alternate days [eg, Mon-Wed-Fri])
  • Duration of treatment: 12 weeks (including escalation periods)
  • Not to exceed 30 mg/dose OR 90 mg/week

Multiple Sclerosis (Lemtrada)

Adult dosage

  • First course: 12 mg/day IV on 5 consecutive days (60 mg total dose)
  • Second course: 12 mg/day IV on 3 consecutive days (36 mg total dose)
  • Subsequent courses: Administer 12 mg/day IV on 3 consecutive days (36 mg total dose) as needed, at least 12 months after the last dose of any prior treatment courses

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Other Drugs Interact with Alemtuzumab?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Alemtuzumab has no noted severe interactions with any other drugs.
  • Alemtuzumab has no noted serious interactions with any other drugs.
  • Alemtuzumab has no noted moderate interactions with any other drugs.
  • Alemtuzumab has no noted minor interactions with any other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your healthcare professional or doctor for additional medical advice, or if you have health questions or concerns.

What Are Warnings and Precautions for Alemtuzumab?


  • Campath: None


  • Patients infected with HIV,
  • Hypersensitivity or anaphylactic reactions to alemtuzumab or excipients
  • Active infection

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Alemtuzumab?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Alemtuzumab?”


  • Therapy associated with moderate emetic potential in adults in the oncology setting; may recommend antiemetics to prevent nausea and vomiting
  • Leukoencephalopathy (PML) reported; withhold therapy immediately for symptoms suggestive of PML


  • Treatment results in severe and prolonged lymphopenia along with an increased incidence of opportunistic infections
  • Prophylaxis does not eliminate these infections; routinely monitor for CMV infection during treatment and for more than 2 months following completion; withhold treatment for serious infections and during antiviral treatment for CMV infection or confirmed CMV viremia (defined as polymerase chain reaction (PCR) positive CMV in more than 2 consecutive samples obtained 1 week apart)
  • Unless an emergency, administer only irradiated blood products to avoid transfusion-associated graft versus host disease
  • Hemolytic anemia, pure red cell aplasia, bone marrow aplasia, and hypoplasia were reported after treatment
  • The safety of immunization with live viral vaccines has not been studied; do not administer live viral vaccines to patients who have recently therapy
  • Serious infusion reactions (pyrexia, chills/rigors, nausea, hypotension, urticaria, dyspnea, rash, emesis, bronchospasm) reported
  • Monitor thyroid-stimulating hormone (TSH) at baseline and every 2-3 months during treatment


  • Therapy can only be administered in certified healthcare settings that have on-site access to equipment and personnel trained to manage infusion reactions (including anaphylaxis, cerebrovascular, cardiac and respiratory emergencies); therapy causes cytokine release syndrome, resulting in infusion reactions that can be life-threatening; in the majority of cases, time to onset may occur within 1 to 3 days of infusion
  • During postmarketing use, cases of vasculitis, autoimmune hepatitis, and Guillain-Barre syndrome reported
  • Autoantibody formation may occur and increase the risk of serious autoimmune conditions (eg, thyroid disorders, immune thrombocytopenia, hemolytic anemia, pancytopenia, glomerular nephropathies, connective tissue disorders, and acquired hemophilia A)
  • Thrombotic thrombocytopenic purpura (TTP) reported, characterized by thrombocytopenia, microangiopathic hemolytic anemia, neurological sequelae, fever, and renal impairment; TTP is associated with high morbidity and mortality rates if not recognized and treated early; discontinue treatment if confirmed or alternate etiology for signs and symptoms cannot be established
  • Chronic inflammatory demyelinating polyradiculoneuropathy reported in the treatment of patients with B-cell chronic lymphocytic leukemia (B-CLL), as well as other autoimmune disorders, generally at higher and more frequent doses than recommended in MS
  • Therapy may increase the risk of other autoimmune conditions because of the broad range of autoantibody formation with therapy
  • Autoimmune hepatitis causing clinically significant liver injury, including acute liver failure requiring transplant, reported; before starting treatment, obtain serum transaminases (ALT and AST) and total bilirubin levels; obtain transaminase levels and total bilirubin levels periodically until 48 months after the last dose
  • Infusion reactions are common (92%) and may be serious or life-threatening; premedication with corticosteroids is required and monitoring
  • May increase the risk for malignancies, including thyroid cancer, melanoma, lymphoproliferative disorders, and lymphoma; patients and healthcare providers should monitor for symptoms of thyroid cancer including a new lump or swelling in the neck, pain in the front of the neck, persistent hoarseness or other voice changes, trouble swallowing or breathing, or a constant cough not due to an upper respiratory tract infection
  • Obtain thyroid function tests, such as TSH levels, before initiation of treatment and every 3 months thereafter until 48 months after the last infusion; continue to test thyroid function after 48 months if clinically indicated or in case of pregnancy
  • Pneumonitis reported; advice patients to contact a physician with symptoms of SOB, cough, wheezing, chest pain/tightness, or hemoptysis
  • Cases of pulmonary alveolar hemorrhage, myocardial ischemia, myocardial infarction, stroke (including ischemic and hemorrhagic stroke), and cervicocephalic (eg, vertebral, carotid) arterial dissection reported; reactions may occur following any of the doses during treatment course; patients should be informed about the signs and symptoms and advised to seek immediate medical attention if any of these symptoms occur
  • Cases of severe and fatal neutropenia were reported within 2 months of infusion; some cases were resolved by receiving granulocyte-colony stimulating factor treatment
  • Increased vigilance and monitoring are warranted in patients previously treated with alemtuzumab (Campath) for CLL who receive Lemtrada for MS; additive and chronic autoimmune effects may occur
  • May increase the risk of acute acalculous cholecystitis; symptoms of acute acalculous cholecystitis include abdominal pain, abdominal tenderness, fever, nausea, and vomiting; leukocytosis and abnormal liver enzymes are also commonly observed; if acute acalculous cholecystitis is suspected, evaluate and treat promptly
  • In the postmarketing setting, cases of cervicocephalic (eg, vertebral, carotid) arterial dissection involving multiple arteries were reported within 3 days of administration
  • Monitor TSH at baseline and every 3 months until 48 months after the last infusion or longer or at any time during therapy if clinically indicated
  • Concomitant use with antineoplastic or immunosuppressive therapies could increase the risk of immunosuppression
  • During postmarketing use, cases of autoimmune encephalitis (AIE) were reported; AIE can present with a variety of clinical manifestations, including the subacute onset of memory impairment, altered mental status, psychiatric symptoms, neurological findings, and seizures; therapy should be discontinued if AIE is confirmed by the presence of neural autoantibodies or an alternate etiology cannot be established

Hemophagocytic lymphohistiocytosis

  • Patients who develop early manifestations of pathologic immune activation should be evaluated immediately and a diagnosis of hemophagocytic lymphohistiocytosis (HLH) considered; discontinue therapy if alternate etiology for signs and symptoms cannot be established
  • HLH is a life-threatening syndrome of pathologic immune activation characterized by clinical signs and symptoms of extreme systemic inflammation; it is associated with high mortality rates if not recognized early and treated
  • Common findings include fever, hepatosplenomegaly, rash, lymphadenopathy, neurologic symptoms (e.g., mental status changes, ataxia, or seizures), cytopenias, high serum ferritin, hypertriglyceridemia, liver function and coagulation abnormalities
  • Hemophagocytosis may be seen on histologic examination of bone marrow, spleen, or lymph nodes; in cases of HLH reported with therapy, most patients presented with fever, elevated ferritin, transaminitis, hypertriglyceridemia, and all patients required hospitalization
  • Although the small number of cases limits the ability to conclude the mean or range of latency for HLH, symptoms have been reported to occur within approximately thirteen months to thirty-three months following the initiation of treatment
  • Patients who develop early manifestations of pathologic immune activation should be evaluated immediately, and a diagnosis of HLH should be considered
  • Discontinue therapy if an alternate etiology for signs or symptoms cannot be established

Acquired hemophilia A

  • Cases of acquired hemophilia A (anti-Factor VIII antibodies) reported; patients typically present with spontaneous subcutaneous hematomas and extensive bruising, although hematuria, epistaxis, gastrointestinal or other types of bleeding may occur
  • Obtain a coagulopathy panel including aPTT in patients who present with such symptoms; patients should be informed about signs and symptoms of acquired hemophilia A and advised to seek immediate medical attention if any of these symptoms occur


  • Infections reported, including herpes viral infections, HPV, tuberculosis, fungal infections (especially oral and vaginal candidiasis), and listeria meningitis; patients with HBV or HCV were excluded from clinical trials
  • In the postmarketing setting, serious, sometimes fatal, opportunistic infections were reported, including aspergillosis, coccidioidomycosis, histoplasmosis, Pneumocystis jirovecii pneumonia, nocardiosis, and cytomegalovirus infections
  • Epstein-Barr virus (EBV) infection, including severe and fatal EBV-associated hepatitis, reported; monitor for signs and symptoms of EBV infections; withhold therapy for EBV reactivation or severe infection
  • Avoid or adequately heat foods that are potential sources of Listeria monocytogenes (eg, deli meat, dairy products made with unpasteurized milk, soft cheeses, or undercooked meat, seafood, or poultry)

Adult-onset Still’s disease

  • During postmarketing use, Adult Onset Still’s Disease (AOSD) reported; AOSD is a rare inflammatory condition that requires urgent evaluation and treatment
  • Patients with AOSD may have a combination of the following signs and symptoms: fever, arthritis, rash, and leukocytosis in the absence of infections, malignancies, and other rheumatic conditions; patients with manifestations of AOSD should be evaluated immediately and treatment discontinued if an alternate etiology for signs or symptoms cannot be established

Pregnancy & Lactation

  • Campath: Unknown whether the drug can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity; administer to a pregnant woman only if needed


  • There is a pregnancy surveillance program; if exposure occurs during pregnancy, healthcare providers and patients are encouraged to report pregnancies by calling 1-800-745-4447, option 2
  • No adequate data on the developmental risk associated with use in pregnant women
  • When administer during organogenesis, the drug was embryo lethal in pregnant huCD52 transgenic mice
  • Auto-antibodies may develop after administration; placental transfer of antithyroid antibodies resulting in neonatal Graves’ disease reported
  • Contraception
    • Women of childbearing potential should use effective contraceptive measures during treatment and for 4 months following that course of treatment
  • Infertility
    • In huCD52 transgenic mice, administration before and during the mating period resulted in adverse effects on sperm parameters in males and reduced number of corpora lutea and implantations in females
  • Clinical considerations
  • Lactation
    • No data on the presence of alemtuzumab in human milk, its effects on the breastfed infant, or the effects of the drug on milk production
    • Lemtrada: Alemtuzumab was detected in the milk of lactating huCD52 transgenic mice administered the drug
    • Consider the developmental and health benefits of breastfeeding along with the mother’s clinical need for the drug, and any potential adverse effects on the breastfed infant from the drug or the underlying maternal condition


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