According to my information, Nystatin is topical, not systemic. It attacks candida on the surface, which makes it useless for an area like the lungs or the eyes. Diflucan is systemic, which means the liver has to metabolize it. My doc reluctantly prescribed a one shot 150 mg dose. Per Medscape, it can go as high as 400 mg daily for 2 weeks, but I think this is desperation dosing. Medscape gives you the range for different treatments. This was for oral candidiasis. The following is from medscape: •Oropharyngeal Candidiasis
Nystatin is used orally in the form of an oral suspension or lozenge for the topical treatment of oropharyngeal candidiasis.
Topical therapy with oral nystatin in the form of an oral suspension or lozenge has been used in the treatment of oropharyngeal candidiasis in patients with human immunodeficiency virus (HIV) infection. Some clinicians consider topical therapy with oral clotrimazole or oral nystatin the treatment of choice for uncomplicated oropharyngeal candidiasis in HIV-infected patients and recommend that systemic antifungal agents (e.g., oral fluconazole, oral itraconazole, oral ketoconazole) be reserved for the treatment of oropharyngeal candidiasis unresponsive to topical agents or for the treatment of severe oropharyngeal candidiasis with esophageal involvement. However, other clinicians prefer to use an oral azole antifungal agent for initial therapy of oropharyngeal candidiasis in HIV-infected individuals. Topical oral therapy with nystatin is ineffective for the treatment of esophageal candidiasis in HIV-infected individuals.
Although oral nystatin has been used for prophylaxis against oropharyngeal candidiasis in HIV-infected individuals†, the drug is no longer included in the prophylaxis guidelines of the Prevention of Opportunistic Infections Working Group of the US Public Health Service and Infectious Diseases Society of America (USPHS/IDSA). If prophylaxis of oropharyngeal candidiasis is indicated in HIV-infected individuals, the USPHS/IDSA recommends oral fluconazole or oral itraconazole solution.
You can see there are differing opinions on its efficacy. It keeps mine in check but 8 years is a long time to use any med. I'd prefer a cure.