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Levamisole Side Effects

For the Consumer

Applies to levamisole: oral tablet

In addition to its needed effects, some unwanted effects may be caused by levamisole. In the event that any of these side effects do occur, they may require medical attention.

Major Side Effects

You should check with your doctor immediately if any of these side effects occur when taking levamisole:

Less common:
  • Fever or chills
  • unusual feeling of discomfort or weakness
  • Black, tarry stools
  • blood in urine or stools
  • cough or hoarseness
  • lower back or side pain
  • painful or difficult urination
  • pinpoint red spots on skin
  • unusual bleeding or bruising

Severity: Moderate

If any of the following side effects occur while taking levamisole, check with your doctor or nurse as soon as possible:

Less common:
  • Sores in mouth and on lips
  • Blurred vision
  • confusion
  • convulsions (seizures)
  • lip smacking or puffing
  • numbness, tingling, or pain in face, hands, or feet
  • paranoia (feelings of persecution)
  • puffing of cheeks
  • rapid or worm-like movements of tongue
  • trembling or shaking
  • trouble in walking
  • uncontrolled movements of arms and legs

Minor Side Effects

Some of the side effects that can occur with levamisole may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

More common:
  • Diarrhea
  • metallic taste
  • nausea
Less common:
  • Anxiety or nervousness
  • dizziness
  • headache
  • mental depression
  • nightmares
  • pain in joints or muscles
  • skin rash or itching
  • trouble in sleeping
  • unusual tiredness or sleepiness
  • vomiting

Levamisole may cause a temporary loss of hair in some people. After treatment has ended, normal hair growth should return.

For Healthcare Professionals

Applies to levamisole: oral tablet


One analysis of 267 reports representing 6,217 patients, found that patients treated for rheumatic disorders (n=1131) reported a significantly higher rate of leukopenia and agranulocytosis (4.9%). The majority of these patients (4.5%) discontinued therapy. Leukopenia is usually not prodromal to agranulocytosis.

Reports show some indication that agranulocytosis is due to a type II reaction (Coombs' classification). Management of levamisole-induced agranulocytosis includes early diagnosis, discontinuation of treatment, and prevention of infection. Agranulocytosis is spontaneously reversible when treatment is discontinued.[Ref]

Hematologic toxicity primarily involves (sometimes fatal) agranulocytosis. Leukopenia has been reported in 2% (over 4,000/mm3), 4% (2,000 to 4,000/mm3), and less than 1% (less than 2,000/mm3). Transient granulocytopenia has been reported in up to 20% of treated patients. Recovery is usually spontaneous. In patients with thrombocytopenia, 1% of patients show platelet counts over 130,000/mm3, and 1% show platelet counts between 50,000 and 130,000/mm3.[Ref]


Dermatologic side effects include dermatitis (8%), alopecia (3%), pruritus (1%) and urticaria (<1%).[Ref]

One analysis of 267 reports representing 6,217 patients, found that patients treated for rheumatic disorders (n=1131) reported a significantly high percentage of idiosyncratic or allergic reactions. These included skin rash (14.8%). Half of the patients experiencing skin rash discontinued therapy (7%).[Ref]


Flu-like symptoms including fatigue (6%), fever (3%), rigors (3%), myalgia, and malaise have been reported.[Ref]

Fever may be a symptom of infection associated with agranulocytosis, but often it is not.[Ref]


Gastrointestinal side effects include nausea (22%), diarrhea (13%), vomiting (6%), stomatitis (3%), anorexia (2%), abdominal pain (2%), and constipation (2%). Flatulence and dyspepsia have also been reported.[Ref]


Cardiac dysfunction leading to edema (1%) and chest pain (<1%) have been reported.[Ref]


Musculoskeletal side effects including arthralgia (5%) and myalgia (3%) have been reported.[Ref]

Nervous system

Nervous system side effects including dizziness (3%), headache (3%), paresthesia (2%), taste perversion (8%), and an altered sense of smell (1%) have been reported.[Ref]


Psychiatric side effects including somnolence (3%), depression (1%), nervousness (1%), insomnia (1%), and anxiety (1%) have been reported. Confusion, hallucinations, impaired concentration, nightmares, and an encephalopathy-like syndrome have also been reported. A case has been reported of a psychotic episode which was believed to be caused by prolonged levamisole use.[Ref]


Ocular side effects including blurred vision (1%) and conjunctivitis (<1%) have been reported. Periorbital edema has also been reported.[Ref]


Infection (5%) has been reported.[Ref]


Hyperbilirubinemia and increased alkaline phosphatase have been reported rarely.[Ref]


Renal failure and elevated serum creatinine have been reported rarely. One case report of syndrome of inappropriate antidiuretic hormone has been reported.[Ref]


Other adverse reactions including vaginal bleeding and anaphylaxis have been reported.[Ref]


1. "Product Information. Ergamisol (levamisole)." Janssen Pharmaceutica, Titusville, NJ.

2. Mutch RS, Hutson PR "Levamisole in the adjuvant treatment of colon cancer." Clin Pharm 10 (1991): 95-109

3. Symoens J, Veys E, Mielants M, Pinals R "Adverse reactions to levamisole." Cancer Treat Rep 62 (1978): 1721-30

4. Moertel CG, Fleming TR, Macdonald JS, Haller DG, Laurie JA, Goodman PJ, Ungerleider JS, Emerson WA, Tormey DC, Glick JH, et al "Levamisole and fluorouracil for adjuvant therapy of resected colon carcinoma." N Engl J Med 322 (1990): 352-8

5. Jeffries JJ, Cammisuli S "Psychosis secondary to long-term levamisole therapy." Ann Pharmacother 32 (1998): 134-5

6. Arora SK, Singh G, Sen PC "Side effects of levamisole." Indian J Med Sci 40 (1986): 6-8

7. Tweedy CR, Silverberg DA, Scott L "Levamisole-induced syndrome of inappropriate antidiuretic hormone." N Engl J Med 326 (1992): 1164

Not all side effects for levamisole may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.