Is significant dizziness a reported side effect of Imuran (Azathioprine)?

Dizziness as a Side Effect of Azathioprine (Imuran)

Yes, dizziness is a reported side effect of azathioprine (Imuran), occurring in approximately 5-30% of patients, and should be monitored as part of routine follow-up for patients on this medication. 1

Evidence on Azathioprine-Associated Dizziness

The British Journal of Dermatology and other authoritative sources have documented that azathioprine can cause several neurological adverse effects, with dizziness being specifically mentioned among the common side effects 1. Dizziness often appears alongside other symptoms such as:

• Nausea and vomiting (12-28% of patients)
• General malaise
• Fever
• Myalgias
• Flu-like symptoms

In some cases, dizziness may be part of a hypersensitivity reaction, which occurs in approximately 5% of patients taking azathioprine 1.

Severity and Management

The severity of dizziness can range from mild to significant:

• Mild cases may resolve with continued use or dose adjustment
• More severe cases may require medication discontinuation
• Dizziness may be part of a more serious hypersensitivity reaction that requires immediate suspension of the medication

Management options include:

1. Administering azathioprine after meals
2. Dividing the daily dose
3. Temporarily reducing the dose
4. Using antiemetics for associated nausea
5. Discontinuing the medication if symptoms are severe or part of a hypersensitivity reaction

Risk Factors and Monitoring

Certain factors may increase the risk of experiencing dizziness and other adverse effects:

• Deficiency of TPMT (thiopurine methyltransferase) enzyme
• Pre-existing liver disease
• Concurrent use of medications like allopurinol or cotrimoxazole
• Higher doses of azathioprine

Recommended monitoring:

• Complete blood counts every 2 weeks for the first 2 months, monthly for the next 2 months, and every 2 months thereafter
• Liver function tests monthly for the first 3 months and then every 2 months
• TPMT level measurement at the start of treatment

Other Neurological Considerations

While dizziness is a recognized side effect, other more severe neurological manifestations have been reported in case studies, though these appear to be rare:

• Headaches 2
• Neuropsychiatric manifestations 3
• Posterior leukoencephalopathy (very rare) 4

Clinical Implications

When a patient on azathioprine reports dizziness:

1. Evaluate the severity and impact on daily functioning
2. Check for other symptoms of hypersensitivity reaction
3. Review complete blood count and liver function tests
4. Consider dose adjustment or medication timing changes
5. If symptoms are severe or part of a broader reaction pattern, consider discontinuation and alternative immunosuppressive therapy

Dizziness should be distinguished from other potential causes, particularly in patients with autoimmune conditions who may have multiple medications or disease manifestations that could cause similar symptoms.