Burmese opposition leader Aung San Suu Kyi has suspended her campaign because of ill-health a week before she is due to stand for a seat in parliament.
A spokesman said she was suffering from low blood pressure and had been vomiting, due to exhaustion, doctors say.
She addressed a crowd of tens of thousands in the port city of Myeik, but will now return home to Rangoon.
She is contesting one of 45 seats in contention in by-elections next week.
Aung San Suu Kyi also complained of sickness during an earlier campaign tour in the north of Burma. Doctors have now advised her to rest.
The opposition leader set herself a punishing schedule, travelling hours in the searing heat by car, and on this most recent trip, by boat, to support her party's bid for a clutch of parliamentary seats, says the BBC's Rachel Harvey.
Suspending the campaign will be an immense frustration to her, and a bitter disappointment to her supporters, tens of thousands of whom have turned out to greet her, our correspondent adds.
The elections - in which Aung Sang Suu Kyi is competing for the first time since 1990 - are being seen as a crucial test of the nominally civilian government's commitment to political reform.
In 1990, Burma's military leaders refused to recognise Ms Suu Kyi's National League for Democracy (NLD) party's election victory.
Polls were initially due to take place in 48 constituencies, but the election commission cancelled ballots in three of them on Friday due to security reasons, reports say.