The Tiger Balm brand was launched in Singapore in 1903 by a Chinese herbalist and is now sold in more than 100 countries.
Pegasus picked up the retained account following a pitch process and is understood to be replacing incumbent agency Myriad PR.
A player in the UK analgesic market, Tiger Balm has two product variations - red and white - and is best known for relieving muscular aches and pains.
The Brighton-based PR agency has been asked to differentiate between the two products among consumers. The campaign will also aim to educate the media and consumers on the use of Tiger Balm White for tension headaches.
According to research firm Mintel, in 2010 the UK analgesics market was worth an estimated £627m, having grown from £620m in 2009.
Tiger Balm is manufactured by Singapore-based Haw Par Healthcare and is distributed in the UK by Ceuta Healthcare.
Peter Reynolds, Ceuta Healthcare marketing manager, said Tiger Balm was undergoing an 'extensive brand awareness programme in the UK', in a bid to drive household penetration and market share.
Pegasus board director Helen Yeardsley said: 'Tiger Balm is an iconic brand, with so many great selling points. We have all encountered it at some stage in our lives, but its targeted relief and strong heritage are not widely recognised.'