The following is a list of items you should consider including in your medical kit – consult your pharmacist for brands available in your country.
Aspirin or paracetamol – for pain or fever
Antihistamine – for allergies, such as hay fever, to ease the itch from insect bites or stings and to help prevent motion sickness.
Antibiotics – consider including these if you're traveling way off the "beaten track". They are prescription drugs so you require to see your doctor and remember to carry the prescription with you.
Loperamides or Diphenoxylate "blockers" for diarrhea and Prochlorperazine or metaclopramide for nausea and vomiting.
Rehydration mixture – to prevent dehydration which can be caused by diarrhea. It is particularly important when traveling with children.
Insect repellent, sunscreen, lip balm and eye drops.
Calamine lotion, sting relief spray or aloe vera – to help ease irritation from sunburn and insect bites or stings.
Antifungal cream or powder – for fungal skin infections and thrush.
Antiseptic such as povidone-iodine for cuts and grazes.
Bandages, band-aids or plasters and other wound dressings.
Scissors, tweezers and a thermometer (note that mercury thermometers are prohibited by airlines).
Syringes and needles in case you need injections and local medical services are not up to an acceptable standard. Ask your doctor for a note explaining why you have them.
Cold and Flu tablets, throat lozenges and nasal decongestant.
Multivitamins – useful when dietary vitamin intake is inadequate.
(Tibet Travel Expert)