It is far better to avoid getting bitten than to rely on internal medicine. And if you live in a malaria region, as I have done, you cannot take pills all the time as it will damage your liver. Anti-malarials can actually ruin a holiday- especially malarone mixed with heat and drink- which can result in spectacular vomiting. If you must take an anti-malarial prophylactic only use the kind you take once a week. Avoid larium except as a cure for when you have real malaria symptoms. I know several people who have developed depression after taking larium. If you are doing a really serious jungle trip and will be away from any kind of hospital then you might pack quinine and larium as a cure not a prophylactic. Chances are, on any other kind of trip, you will be near a hospital either at home or abroad that can treat you.
I have spent time in jungle houses with people who have malaria and I've avoided it, so far, so this advice may actually prove very useful.
1. Avoiding being bitten is far better than any kind of internal medicine. If you know there are mosquitoes around and to avoid being bitten, cover up with baggy clothing- forget shorts and short sleeved shirts- wear lightweight big size long sleeve shirts and cargo pants, and wear a head net if necessary. Wear a bug jacket if you have to- this is a net jacket that covers everything. If you want to wear shorts you can also get bug trousers- check the Net or North American stores for these.
2. Get a decent mosquito net, or better, sew a big baggy head and arm covering net to your sleeping bag or sheet inner top – add ties so that it can be attached to a hammock or tent and hang down over you without brushing your face. The worst bites are always at night.
3. Everywhere you can buy those green anti-mosquito coils. They work best in pairs- but if there is no air circulation you will get up next day with a headache.
4. Plug in heaters which are loaded with a tablet of insect repellent are also great in infected hotels- If you get the kind you add liquid to these work for longer. It’s often a toss up between limiting further insect access or getting enough air to breathe. I’ve found sometimes you can limit a lot of mosquito action by just shutting the bathroom window and door.
5. Half an hour before sleep go into your tent and blast it with full strength aerosol insect killer- the highly nasty stuff. By the time you go to bed the damaging insecticide will have settled. And all the bugs will be dead. You can do this in hotel rooms too.
6. On hiking trips I don’t really wash that much. I get fairly grubby and I don’t use scented soap. This patina of filth (hands and face cleaned only) seems to direct mossies to my cleaner pals. No science but it works.
7. I also stand in the smoke of wood fires whenever I can. You see native Americans doing this all the time. Not only do you not get bitten at the time, you also carry the wood smoke smell which deters them later on.
8. I never wear open sandals at night- always get bitten down there otherwise. Worst is being in an outdoor restaurant with your feet being eaten at the same rate as you are eating the house special.
9. Deet really works. 50% is fine and doesn't dissolve your watch strap or kill your eyes when it gets in them- as it will when you sweat- unlike 100% strength. You can mix deet with vaseline to get it to stay longer on the skin. What I do is simply drench my cuffs and shirt collar and hat- since my only exposed areas are hands and face and I'd rather not have deet directly on them. Deet'll wear off all too quickly but it's good to have some around.
Thus armed you will be fine: let battle commence!