In the Ranma manga quite a few potions, powders, plants, incense, and chemicals are used by the characters including Ranma.
Here is an incomplete list (since I think I forgot some - also not listed some technological items, magical items not in powder or potion form, spirit/kami/ghost powered items, pressure points, and those from the anime or games that were not in the manga):
-knock out powder
-dream sleep incense
-mushrooms of aging
-mandrake root also called mandragora
-poison flower of enfeeblement
-flower of adoration medicinal plant
-combine the last two and you have the flower of womanhood turning the wearer into a perfect housewife
-poison snake herb
-bean throwing plant
-toushintan - fighting instinct rises can not disobey the command to fight (used on Konatsu to get him to fight Ranma)
-forgotten by me or unnamed poisons (like the ones that were shown but not used or were avoided), unnamed antidotes (like the extremely hot one that swelled up Ranma's lips), unnamed medicines (like the one the sick boy took) and plants (like the giant plants or plant with the poisonous pollen or even just the regular not in anyway strange plants like trees and flowers that the characters used or had for one reason or another such as the flowers given by Akane to Ryoga when she thought he was sick or the ones given to Shampoo during the reversal jewel arc).
I don't see very many fics that use these types of things even though they are often used by the characters in the manga. The reason I thought up making this list at this time is because of email conversations about another series that did not really use these types of things even though the characters were students being taught how to make these types of things and wondering why these things (like many other things) aren't used in fan fiction more often.
I would expect that Ranma and some of the others who go off training to be carrying quite a few of these type of things (evidence from the manga would agree with some of these). I would expect Ranma to carry, when going on a trip in his back pack, a first aid kit containing various pharmaceuticals, herbal remedies (such as plants that would be grounded up and made into a paste to reduce bruising and swelling of which there are quite a few and many work as well or even better then the store bought ones), potions (Happosai is shown to have books on potions and Ranma and the Tendo's are shown to go through Happosai's stuff like during the martial arts dining arc or the moxibition of weakness arc), teas that serve a purposes (there are a lot of medicinal teas and Asians in particular use them often), incense (Ranma used incense a few times like the suggestion incense used on Happosai but is also shown to have and use incense at other times since we see him have it burning near him on occasion), pills (several were shown in the manga like the master student pill or the phoenix pill and over the counter medicine most often is in pill format) etc. Beyond the above mentioned items here are some more things I think he'd have in one format or another (over the counter, herbal, a potion that does it, etc.):
medicines and bandages
-pain relievers mostly over the counter such as asprin but also prescription ones like morphine
-bright flash/flash bomb (made from aluminum powder and potassium percholate maybe)
-fireworks that make a loud noise
-glue like Happosai's friend used
-stamina/energy drinks (the Japanese really like these for some reason, personally I can't stand them)
If someone, such as me, were to include these types of things in a fanfic what other effects do you suppose a potion or plant would have? Basically I'm asking you to suggest possible potions, powders, and plants properties preferably strange ones rather than say pharmaceuticals or what could easily be found in a book on herbal remedies (not looking for magic items or spirit powered items of which there also were quite a few in the manga).
Almost forgot. Aphrodisiacs of which very few were shown in the manga (at least that I remember). The only one I can remember showing up in the manga was Mamushi-zake (snake in drink). Ranma's clone in the mirror arc has this. Mamushi-zake is an old folk remedy made by soaking a mamushi (snake) in sake or other alcoholic beverage for about a year it supposedly increases sexual stamina.