Greek train and ferry services stopped and hospital staffing was cut to a minimum on Thursday as transport workers and doctors protested against spending cuts imposed to meet the country's bailout terms.
As the economy enters a sixth successive year of recession, demonstrations and strikes have surged again over the latest round of measures.
Public transport in Athens was disrupted as bus, trolley bus and railway workers stopped work while ships and ferries stayed docked at ports after seamen began a 48-hour strike.
Hundreds of doctors, medical staff, teachers and municipal workers rallied in central Athens to protest against "dangerous" measures that they say have drained the nation's health system of supplies and staff.
They later marched to parliament chanting "We will strike until we win!" and holding up banners reading "We'll kick the troika out," referring to the country's lenders, the European Union, International Monetary Fund and European Central Bank.
Greece's main public sector union ADEDY also called a work stoppage. "Belt-tightening is killing the people and destroying the national health system," said its head, Costas Tsikrikas.
Highlighting how little households have to spend, data on Thursday showed retail sales dropped by almost a fifth in November from last year.
Later on Thursday, private sector union GSEE kept up the pressure on the government, calling a 24-hour anti-austerity strike for February 20.
In a separate protest, about 1,000 supporters of the Communist-affiliated PAME group gathered outside an Athens court to show solidarity with activists arrested for storming the labor ministry's office on Wednesday.
Prime Minister Antonis Samaras has sought to maintain a hard line against strikes and protests to show the country's foreign lenders - as well as the public - that he is determined to push through unpopular reforms.
A nine-day walkout by metro workers led to a standoff with his government this month and paralyzed transport across the Greek capital. The strike ended only after the government invoked an emergency law and threatened to arrest the workers.
The lenders' decision to disburse long-delayed aid last month eased fears that Greece could go bankrupt and be forced to leave the euro zone, but the social climate is volatile.
The country's two main unions, which combined represent about half its workforce, have called repeated strikes since the debt crisis broke out in 2009. ADEDY is expected to join the anti-austerity strike next month.
"We'll keep fighting," said Tsikrikas. "We demand that Europe's heavyweights change their dead-end policy."
(Additional reporting by Tatiana Fragou; Writing by Deepa Babington; Editing by Ruth Pitchford)