The duration of taking tenofovir is related to the disease being treated, for example, hepatitis B patients can take this drug for long-term treatment. Tenofovir is an oral antiviral drug, can effectively inhibit the replication of the virus, with strong antiviral effect, low side effects, not easy to drug resistance, can be used in the treatment of hepatitis B, AIDS. It can be used for the treatment of hepatitis B and AIDS. Taking tenofovir for antiviral treatment can achieve significant effect in 15-20 days. Patients with hepatitis B can take tenofovir for long-term antiviral treatment if their financial condition allows, but it is rare for patients to turn negative for hepatitis B. AIDS patients can also take tenofovir for a long time to inhibit the replication of HIV and control the development of the disease. But older, renal insufficiency, diabetes patients long-term use of tenofovir can cause liver and kidney damage, should be used with caution, the process of taking the drug need to regularly check liver and kidney function.