Check with your doc as there are side-effects, imo you'd rather have the side-effects than maleria and it it's advisable to take them when you're not staying in the area for long.
Don't take any chances. I know of one hardcore dude who was in tears due to pain from malaria. And by hardcore I mean the type of person who could probably do a self amputation with a pocketknife.
In Kenya you get the rainy season in April so all areas are risky. I got infected in Lamu and I was taking doxy at the time. These meds all have side effects and only provide 80% protection. Malanil (Malarone) is expensive but maybe least hassle as said. Then again I know people who take precautions at dusk and dawn and wear pesticide washed clothing, sleep under pesticide drenched nets and spray themselves with citronella and wear long pants and sleeves and don't pop pills.
Seekers Travel at Fourways Crossing operates a Travel Clinic. There is no charge for a consultation apart from the cost of the medication. You can telephone them at 011-790-0000 to get more information. Malanil seems to be the treatment of choice at the moment but it is quite expensive.