Officials have registered 2,054 cases, with the capital Conakry and the south-western city of Forecariah worst affected.
Thirteen people have died in Conakry and 23 in Forecariah.
The NGO Doctors Without Borders said in a statement it had increased the number of hospital beds to "soon reach 600 to
prepare for the height of the outbreak".
Two other organisations, Unicef and Action Against Hunger, have donated hygiene kits containing soap and chlorine to purify water.
Guinean health authorities are also running local awareness campaigns in a bid to stem the outbreak.
Poor water and sanitation systems give rise to the disease, an acute intestinal infection caused by ingesting contaminated food and water which causes acute diarrhoea and vomiting and can kill in hours, according to the World Health Organisation.
Sierra Leone, Mali and Niger have also been hard hit, with high levels of malnourishment as a result of a drought exacerbating the problem.