<p>The most common side effects of adefovir dipivoxil are weakness, headache, stomach pain and nausea. Severe acute exacerbations of hepatitis have been reported in patients who have discontinued anti-hepatitis B therapy, including therapy with adefovir dipivoxil. In patients at risk of or having underlying renal dysfunction, chronic administration of adefovir dipivoxil may result in nephrotoxicity. Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogs alone or in combination with other antiretrovirals.</p>