An Aedes aegypti mosquito, which is responsible for spreading Zika virus, is seen through a microscope. Photograph: (Getty)
The latest guidelines come after the health body found evidence of the virus remaining in semen longer than previously thought
People returning from Zika-hit regions should practice safe sex for six months after that, World Health Organisation (WHO) said.
The UN health body said people who show no symptoms should follow the advisory.
Couples or women planning pregnancy should wait for six months before they go ahead with their plan, the guidelines further stated.
In June, a WHO guideline had recommended men to practice abstinence or have safe sex for eight weeks after their return from an affected region.
But new findings have shown the virus to remain in semen longer than previously assumed. The guidelines stated that Zika has been found in semen for as long as 188 days.
As of August 26, 11 countries have reported cases of Zika which has been transmitted mainly through vaginal intercourse.
"Mounting evidence has shown that sexual transmission of Zika virus is possible and more common than previously assumed," the WHO said in the updated guidelines.
The new recommendations will remain valid till November 2016, unless new findings bind the health body to further broaden or scale down its guidelines.
Zika is a disease which shows no symptoms in four out of five symptomatic people. Pregnant women are the worst-affected as their babies have a high risk of developing head and brain defects, a condition known as microcephaly.
The virus is spread by daytime-active Aedes mosquitoes.