The statement said that a recent physical "was normal and she is in excellent mental condition."
In a letter released by the campaign, Clinton's longtime physician, Lisa Bardack, who visited with Clinton at her home on Wednesday, said Clinton's pneumonia diagnosis on Sept. 9 started as a "low grade fever, congestion and fatigue."
Bardack wrote that after Clinton's travel, which included numerous flights on her new campaign plane, her congestion worsened and she developed a cough, evidenced by a coughing attack during a campaign rally in Ohio on Labor Day. When Clinton returned home to New York, her doctor performed a CT scan, which revealed pneumonia.
Bardack added that she has evaluated Clinton several times since she became "overheated" at a 9/11 memorial ceremony and that she is "recovering well with antibiotics and rest." Clinton currently takes a handful of medications, including for her thyroid, and Bardack said "she continues to remain healthy and fit to serve as president of the United States."
Bardack also revealed that in January as Clinton was campaigning before the Iowa caucuses, she developed a sinus and ear infection and had a tube placed in her left ear to help drain fluid from her middle ear. Clinton reported having "significant improvement in her symptoms" since this procedure.
Clinton's campaign, in an attempt to downplay questions over her health, insisted recently that the presidential nominee has "no other undisclosed condition" and promised to release more information about her medical records.
Last summer, Clinton released a two-page statement from Bardack, saying "she is in excellent physical condition and fit to serve as president of the United States."
Clinton, following her doctor's advice to rest and modify her schedule this week, canceled her plans to campaign on the West Coast and has remained at home in Chappaqua, New York, since Sunday.
She is scheduled to return to the campaign trail on Thursday, with a campaign event in Greensboro, North Carolina.