some medical answers
Not a Doctor yet (1 yr to go!) but for what its worth:
Iodine: is a topical (use on skin surface) antiseptic/microbicidal. Don't carry a bottle of it. You can buy prep-pads or swab sticks. Better yet, buy the Betadine ones (a povidone-iodine solution that is a bit stronger). This would be handy in case of blisters, bug bites, cuts, scrapes etc, esp when you dont have the proper hygenic conditions to care for them.
Melatonin: is a hormone naturally secreted by your pineal gland (in response to light) to regulate sleep rhythms. I've heard there are synthetic supplements available, but it seems a bit extreme to take it. I wouldnt take any hormones unless it was absolutely neccessary. Why put that into your body. If you have sleeping problems, best take Valerian root tincture/herbal supplements.
"Mycins" refer to a number of different antibiotics like Vancomycin, Streptomycin etc (prescription only). Antibiotics are taken for specific infections and are not to be carried "preventively" as you risk developing antibiotic-resistant strains of whatever you're infected with.
Anti-fungal agents usually end in "azole" as in Fluconazole, Miconazole. If you have a known fungal infection, just take whatever your Dr has prescribed (eg Lamisil for a toenail inf etc).
My personal reccommendation si Cortaid for everyone! Or just your simple tube of Hydrocortisone. Apply on any bite, rash, hive, redness and kaboom! A wonderful anti-inflammatory ointment.
peace and goodness to all!
amaris