Key points
- Healthcare providers should consider a patient's medical history, clinical signs, nutrition, and immune system status when treating Giardia infections.
- Multiple types of medications effectively treat Giardia infections.
- There are several factors to consider before switching a patient's treatment plan.
Treatment options
Diagnosing giardiasis can be difficult. Healthcare providers sometimes decide to treat patients based on appropriate history and clinical signs of giardiasis. Healthcare providers should talk with patients about their treatment options.
There are different factors that can shape how effective a drug regimen will be for each patient. Some of these factors include:
- Medical history
- Nutritional status
- Immune system condition
Medication options
Several different types of medications can treat Giardia infections. However, some of these medications may not be readily available in the United States.
Effective medications include:
- Tinidazole
- Nitazoxanide
- Metronidazole
Other medications healthcare providers can use to treat Giardia infection include:
- Albendazole
- Mebendazole
- Paromomycin
- Quinacrine
- Furazolidone
Prevent dehydration
Treatment for ongoing and recurrent infections
People treated for giardiasis may continue to have symptoms or positive tests for Giardia. In these cases, healthcare providers should consider the following steps before switching therapies:
- Determine if the patient is still infected. Test 3 stool samples over several days by antigen testing or microscopy.
- If a laboratory does not find Giardia after 3 stool exams, it is likely that the patient is no longer infected. Unfortunately, some patients may continue to have symptoms for weeks to months after the infection has cleared.
- If the patient tests positive, consider possible reinfection rather than treatment failure. People can get reinfected through the environment, like their home or childcare facility, or from other household members.
- Consider inadequate dosing and duration of treatment. Confirm that the patient took the entire course of medication as prescribed.
- Consider combination therapy using medications from different classes if Giardia is confirmed by a positive stool test, you have ruled out reinfection and inadequate dosing, and the patient still has symptoms. Combination therapy can be safe, effective, and useful in the case of treatment failure. Wait at least 2 weeks after the patient takes the last dose of anti-Giardia medication. Then, reexamine the patient's stool samples for Giardia as described in step 1 above.
- If the patient's stool samples still remain positive for Giardia even after combination therapy, consider an underlying immunodeficiency that may be preventing the patient from clearing the infection. You might consider conducting a workup for other diseases during a combination therapy regimen.