In all cases
Antidiarrheal
Pain relief
Paracetamol
Disinfectant
Wide-spectrum antibiotic (by prescription)
Cream to treat burns
High-protection sunscreen
Collyrium
Antihistaminic
Local anti-inflammatory drug
Antispasmodic
Antiemetic (in order to avoid car sickness, for instance)
Your usual oral contraceptive, condoms
Depending on the destination
Antimalarial drugs
Water disinfectant (ex. hydroclonazone)
Single-use syringes
Equipment
Disinfectant wipes or gel
Sterile band-aids, adhesive plaster and bandage
Safety pins and round tip scissors
Elastoplast
Hemostatic compresses
Tweezers
Insecticide
Tampons or sanitary towels
Hat
Raincoat
Treated mosquito net, if necessary
