Martha Beatriz Roque tells The Associated Press she will not accept any medical attention.
The 67-year-old opposition activist has also stopped taking medication for her diabetes, adding to concerns for her health. At least a dozen other dissidents have joined her on the strike that began Monday.
Roque is demanding the government release a little-known dissident who she says was supposed to leave jail Sunday, and make several other concessions. Roque said Wednesday she is prepared to die.
The government has had no comment. It considers members of the opposition to be common criminals paid by Washington to stir up trouble.