But the group's leaders remained defiant, announcing a day of meetings on Thursday to discuss tactics, followed by an evening of music and dancing aimed at keeping spirits and numbers high.
"We will have cultural performances on this stage from each region, in order to strengthen relationships of our Red Shirt people," Nattawut Saikur, a protest leader told crowds on Wednesday evening.
He also said the demonstrations would on Saturday "spread out on every road across Bangkok to appeal to more people to join us".
Most of the red shirts, also known as the United Front for Democracy Against Dictatorship (UDD) are supporters of deposed prime minister Thaksin Shinawatra.
They have so far failed in their drive to bring down the government, despite spilling bottles of their own blood outside the entrance to the home of Abhisit Vejjajiva, the Thai prime minister, in a symbolic protest against the government.
On Tuesday, they collected hundreds of litres of their own blood that was symbolically spilled at the gates of Government House.
The red shirts are campaigning to bring down Abhisit's government, which came to power via a December 2008 parliamentary vote after a controversial court ruling ousted Thaksin's allies.
The mainly poor and rural followers of Thaksin, a billionaire telecoms tycoon who lives abroad to avoid a jail term for corruption, fervently support the populist policies he introduced before his ouster in a 2006 coup.
Government reaction to the bloody spectacles over the past two days has been muted, but a minister attached to the prime minister's office said it was "uncivilised".
|Protest organisers remain defiant promising further demonstrations [AFP]
"Blood is a symbol of violence and hurling it at the house is saddening. The prime minister is speechless over this incident," Satit Wongnhongtaey told reporters.
The red shirts are protesting against the perceived elitism and illegitimacy of the Abhisit government.
Abhisit has twice rejected the protesters' demand to dissolve parliament, saying he must think of the country's interests and not only those of the red shirts.
Thailand has been in political turmoil since early 2006, when anti-Thaksin demonstrations began.
In 2008, when Thaksin's political allies came back to power for a year, his rival "yellow shirt" protesters occupied the prime minister's office compound for three months and seized Bangkok's two airports for a week.