The consumer health and hygiene group said net revenues rose 7pc to £2.52bn in the three months to the end of March, compared with analysts' average forecast of £2.47bn.
An intense North American flu season has pushed up demand for hospitals, pharmacies and makers of cold remedies.
"Although the flu season undeniably helped first quarter sales performance, it is the non-flu related areas of the portfolio that were more impressive," they said.
"The home and hygiene products comfortably produced their best life-for-like in many quarters and to a level last seen when market growth rates and the competitive environment were more favourable, sometime in early 2008."
The hygiene sector grew 9pc on a like-for-like basis, driven by sales of Dettol and Lysol disinfectant, Reckitt said.
The group, which also makes household cleaning products such as Cillit Bang, has been shifting its focus to the faster-growing health and hygiene sector. It is also targeting emerging markets and wants them to make up half its sales by 2015, compared with the current 44pc.
Rakesh Kapoor, chief executive, said: "We are pleased with a strong start to the year, with our health and hygiene brands leading Reckitt Benckiser's growth across all geographies."
He told analysts on a call that "there could be a slowdown", but said overall the business continued to perform well, highlighting brands such as Vanish cleaner in Brazil and Durex condoms in China.
Reckitt maintained its group revenue growth forecast for 2013 of between 5pc and 6pc.
Shares in Reckitt, which hit a record high of £48.12 in March, rose 15 to £47.24 in morning trade.