Are there other good drugs, natural or otherwise that are good to prevent dvts and pe when on long flights besides aspirin?

Yes: There are many natural blood-thinners, including vitamin e, fish oil & curcumin. The best alternatives to Aspirin are enzymes such as nattokinase, lumbrokinase and proteolytic enzymes like wobenzym & vitalzym. Pharmaceuticals like Coumadin (warfarin) & Heparin can prevent dvt's too. Moving/stretching your legs frequently & staying well-hydrated are also key measures in preventing clots on long flights.

Yes: Although it is rare to need medications during long flights, the only medications that have been proven to be effective are prescription anticoagulants (blood thinners). Aspirin and non-prescription, natural remedies have not been shown to be effective. If you have a medical condition that increases your risk, your physician can determine if you need a blood thinner before flying.

A few things to do: As dr. Roth said, there are only approved blood thinners that can be used. Short of that though, stay well-hydrated, walk around, avoid alcohol use, do leg, ankle and foot movement exercises against some kind of resistance, and use graduated compression stockings (not teds) on long flights, as dr. Baker mentioned.