In 2009 I was in Africa and got Malaria while taking Doxycycline. That was the last time I took a prescription drug for Malaria prevention. I travel to Africa every year for 6-8 weeks and have taken Demal200 for the past 9 years and have never gotten Malaria again. I love how simple this is to take and that the bottle last for multiple trips and years. Great product!!!!