By Ania Lichtarowicz
BBC health correspondent
The World Health Organisation (WHO) is warning that some countries are likely to face a shortage of malaria drugs because of a sharp increase in demand.
Mosquito bites transmit malaria
The medicines - derived from a Chinese herb - are used to treat the deadliest form of the disease.
The WHO says 40 countries who now use artemisinin derived drugs as first-line malaria treatment could be affected until March next year.
It says that availability of second-line treatments should be increased.
The problem lies with the raw material - it takes six months to grow the herb plant which produces artemisinin and another three to five months to process it.
Things weren't so bad in 2001 when this type of treatment was approved - just over 200,000 treatments were ordered at the time.
But now 10 million courses are wanted and by next year this is expected to rise to over 60 million.
Novartis - the drug company who makes it - says Chinese suppliers cannot keep up with demand.
The WHO is promising to help any country facing a shortage, but is recommending that availability of second-line treatments like quinine should be increased.
Although more difficult to use, it's effective against the most deadly form of malaria.