Nausea and vomiting

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    Eto or Pto, PAS, Z, Amx/Clv, Cfz, Lzd, Ipm/Cln or Mpm, Bdq
     

    Nausea and vomiting are frequent, especially with Eto or Pto and PAS during the first few weeks of treatment. To avoid nausea and vomiting, these drugs can be initiated at low dose with gradual increase over one to 2 weeks.

    • Always look for:
      • Signs of dehydration (thirst, dry mouth, sunken eyes)
      • Serum electrolytes disorders if vomiting
      • Signs of hepatitis
      • Haematemesis and melena
    • Dehydration and electrolyte disorders should be corrected as necessary.
    • Treat nausea and vomiting aggressively, using a stepwise approach:

    First phase - Adjust administration of the responsible drug

    • Administer the suspected drug(s) causing nausea at bedtime.
    • Patient on Eto or Pto: stop for 3 to 4 days. If signs improve, gradually resume at a lower dose (250 mg, then if tolerated, 500 mg and so on until the full dose is reached).
    • Patient on PAS: stop for 3 to 4 days. If signs improve, gradually resume at a lower dose (2 g, then if tolerated, 4 g and so on until the full dose is reached). Take PAS one hour after taking other TB drugs. If PAS is taken once daily, take in 2 divided doses.
    • Encourage the patient: nausea and vomiting often improve over the first weeks and may resolve entirely with time.

    Second phase - Administer an antiemetic

    ondansetron PO 30 minutes before TB drugs:
    Child 6 months to < 2 years: 2 mg once daily
    Child 2 to < 4 years: 2 mg 2 times daily
    Child 4 to < 12 years: 4 mg 2 times daily
    Child ≥ 12 years and adult: 4 to 8 mg 2 times daily
    Ondansetron is a QT prolonging drug and should be avoided in patients on Cfz, Bdq, Mfx, Dlm, Lfx.

     

    In adults, when ondansetron is not available or is to be avoided:
    metoclopramide PO:
    Adult < 60 kg: 5 mg 3 times daily
    Adult ≥ 60 kg: 10 mg 3 times daily
    The interval between each dose should be at least 6 hours (even in the event of vomiting). Do not use metoclopramide if neurological problems develop.
    or
    promethazine PO 30 minutes before TB drugs:
    Adult: 25 mg

    Third phase - Reduce the dose or temporarily stop the responsible drug

    • Patient on Eto or Pto: if the patient does not tolerate full dose, avoid giving an adult less than 500 mg daily.
    • Patient on PAS: if the patient does not tolerate full dose, avoid giving an adult less than 6 to 8 g daily.
    • Patient on Cfz: reduce the dose by half.
    • In the event of intractable nausea and vomiting despite dose reduction or interruption of the suspected drug, stop all TB drugs for 3 to 4 days, until signs resolve.

    Permanent interruption of a drug should only be considered if it is not essential to treatment.

     

    Note: if there is excessive anxiety over the nausea caused by TB drugs, consider adding diazepam PO (adult: 5 mg 30 minutes before TB drugs). This can help to avoid "anticipation nausea". The treatment must be short as benzodiazepines may cause dependence and tolerance. Do not exceed 10 days of treatment.

     

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