Nito Alves (17) was arrested on September 12 for printing slogans on T-shirts which prosecutors say insulted Dos Santos, Africa's second longest-serving leader after Equatorial Guinea's President Teodoro Obiang Nguema Mbasogo.
One of the slogans called the president a "disgusting dictator" and the other was a quote from a local journalist about war being necessary and urgent in Angola to bring democracy.
The teenager has started a hunger strike to put pressure on authorities to release him, his lawyer said on Wednesday.
"The hunger strike worries us as the situation in the jails is not good and there are many problems, especially regarding medical assistance, so he will suffer," Salvador Freire Santos, one of Alves's lawyers, said.
Alves is a member of a youth movement that has held several protests since March 2011 calling for Dos Santos to resign after 34 years at the helm of Africa's number two oil producer. The movement accuses the president of suppressing Angolans' rights and not doing enough to tackle widespread poverty.
Global rights group Amnesty International and local activists have urged the authorities to release Alves.
Shared cells with adults
Freire Santos added: "Just on Tuesday we made another request with prosecutors for his release based on the argument that he can only be kept detained for 45 days and should now await trial in freedom."
Alves is at the Viana prison in the capital's suburbs. His lawyer said it was better than the central Luanda jail where he was held initially and where he shared cells with adult prisoners, many of whom were convicted of multiple crimes and deemed highly dangerous.
The lawyer said that while Angola's justice system is very slow he expects the case to be brought to trial rapidly due to pressure from both inside and outside the country. – Reuters