Continuing with Aetius of Amida's pharmacy and its parallels: onions.

Philumenus on onions as a cure for bites of all kinds.

"For dog bites or people bites, apply a poultice of fine salt mixed with honey until the bite is filled. Some also add onion and vinegar and then use it."

πρὸς οὖν κυνόδηκτα καὶ ἀνθρωπόδηκτα ἅλας λεῖον σὺν μέλιτι κατάπλασσε, ἄχρις οὗ πλήρη ᾖ. τινὲς δὲ καὶ κρόμμυον προσμίσγουσιν καὶ ὄξους καὶ οὕτως χρῶνται.

Philumenus, On poisonous animals and their remedies [De venenatis animalibus eorumque remediis], 5.6 (10,7-9 Wellman)

Galen on onions.

"The onion belongs to the fourth degree of things that heat. Its substance is composed of rather large particles, which is why it also opens up hemorrhoids when it is applied; when used full strength with vinegar in the sun, it washes away skin lesions; and when rubbed on bald spots, it stimulates the hair faster than alcuonium. If one separates off its juice, whatever remains is a considerably earthy, hot substance, but the juice itself is a watery and airy hot substance. Thus, when it is used as a salve against thick humours, it benefits cataract sufferers and those who are short-sighted. Due to its mixture, the onion generally causes flatulence when eaten, and for this reason, those which are drier in their mixture cause less flatulence."

Κρόμμυον ἐκ τῆς τετάρτης ἐστὶ τάξεως τῶν θερμαινόντων. ἡ δ' οὐσία παχυμερής ἐστιν αὐτοῦ μᾶλλον, ὅθεν καὶ τὰς αἱμοῤῥοΐδας ἀναστομοῖ προστιθέμενον καὶ σὺν ὄξει καταχριόμενον ἐν ἡλίῳ τοὺς ἀλφοὺς ἀποῤῥύπτει καὶ παρατριβόμενον ἀλωπεκίαις θᾶττον ἀλκυονίου παρορμᾷ τὰς τρίχας. εἰ δ' ἀποχωρίσειεν αὐτοῦ τις τὸν χυλὸν, ὅσον μὲν ὑπόλοιπον ἱκανῶς ἐστι γεώδους οὐσίας θερμῆς, αὐτὸς δ' ὁ χυλὸς ὑδατώδους τε καὶ ἀερώδους θερμότητος. οὕτω οὖν καὶ τοὺς ὑποχεομένους καὶ ἀμβλυώττοντας ἐπὶ πάχει χυμῶν ὀνίνησιν ὑπαλειφόμενος. ἐκ δὲ τῆς τούτου κράσεως ὅλον τὸ κρόμμυον φυσῶδές ἐστιν ἐσθιόμενον, καὶ διὰ τοῦτο ὅσα ξηρότερα τὴν κρᾶσιν ἀφυσότερα.

Galen, On the mixtures and capacities of simple drugs, 7.58 (XII 48-49 Kühn)

Oribasius' concise summary.

"Onion belongs to the fourth rank of things that heat. Its substance is composed of thick particles."

Κρόμμυον ἐκ τῆς τετάρτης ἐστὶ τάξεως τῶν θερμαινόντων· ἡ δὲ οὐσία παχυμερής ἐστιν.

Oribasius, Collectiones medicae, 15.1.10.79 (260,26-28 Raeder)

Aetius' entry based on Galen.

"Onion belongs to the fourth degree of things that heat. Its substance is composed of very large particles, whence it also opens up hemorrhoids when it is applied; when used full strength with vinegar in the sun, it washes away skin lesions; and when rubbed on bald spots, it stimulates the hair faster than alcuonium. When eaten, it heats the body with its acridity and thins thick and sticky humours in it. It fills the abdomen with air because its substance is composed of very thick particles."

Κρόμυον ἐκ τῆς τετάρτης ἐστὶ τάξεως τῶν θερμαινόντων· ἡ δὲ οὐσία αὐτοῦ παχυμερὴς μᾶλλον, ὅθεν καὶ τὰς αἱμορροίδας ἀναστομοῖ προστιθέμενον καὶ σὺν ὄξει καταχριόμενον ἐν ἡλίῳ τοὺς ἀλφοὺς ἀπορρύπτει καὶ παρατριβόμενον ἀλωπεκίαις θᾶττον ἀλκυονίου παρορμᾷ τὰς τρίχας. ἐσθιόμενον δὲ θερμαίνει μὲν τὸ σῶμα τῇ δριμύτητι καὶ λεπτύνει τοὺς ἐν αὐτῷ παχεῖς καὶ γλίσχρους χυμούς· ἐμπνευματοῖ δὲ τὴν γαστέρα διὰ τὸ παχυμερὲς τῆς οὐσίας.

Aetius of Amida, Libri medicinales, I 232 (97,14-20 Olivieri)

Cf. Dioscorides, De materia medica, 2.151 (p.155 in Beck), which mentions many of the other uses of onions as well, adding to what is said above that it's useful for blisters on the feet (when it is mixed with chicken fat, hardness of hearing, sore throats, and stuffy noses, but that it causes headaches. He leaves out the part about people bites. Oddly, none of these passages mention the fact that onions make your cry, a fact that Aristotle's school was rather interested in:

(pseudo-)Aristotle on why onions cause tears, while garlic does not.

"Why is it that only onions cause the eyes to sting so excessively? People even say it got its name because of this, since [κρόμμυον] makes the pupil close [τὴν κόρην συμμύειν]. Marjoram doesn't, nor do other things which are acrid. Thus, watercress [lit. "up the nose"], because it is hotter, causes more drying than the colliquescence that it produces, since it produces tears in those who eat it; it does not, however, [produce tears] when it is brought close by, because it does not give off any thin vapour, for it is too dry and hot. Marjoram and similar hot things are dry and mild, but what is going to produce tears needs to be stinging, moist and sticky. For this reason, olive oil produces tears, although its stinging is weak. For because of its stickiness and fineness, it produces pain when it penetrates [the flesh], and produces liquefaction because of the pain. The onion has a similar capacity, hence the moisture and vapour from it is hot, fine and sticky. Thus, when it is brought close by, because of the kind of vapour that it is and because it carries with it a fine moisture, it produces tears; when it is eaten, the exhalation passes through […there is a lacuna here…]. Garlic is hot and acrid and has moisture, but it is not sticky, so it does not produce tears.

Διὰ τί τὸ κρόμμυον μόνον οὕτως περιττῶς δάκνει τὼ ὀφθαλμώ (διὸ καὶ τοὔνομά φασι τοῦτ' ἔχειν αὐτό, ὡς τὴν κόρην ποιεῖν συμμύειν), ἡ δὲ ὀρίγανος οὔ, οὐδ' ἄλλα δριμέα ὄντα; καὶ γὰρ τὸ ἀνάρρινον μᾶλλον δάκνον οὐ ποιεῖ ὁμοίως δακρύειν προσφερόμενον, τὸ δὲ προσφερόμενον καὶ κατατρωγόμενον. ἢ ὅτι διαφοραὶ πολλαὶ ἀκολουθοῦσιν ἑκάστοις τῶν δριμέων, ἃ ποιεῖ τὴν ἰδίαν ἑκάστου δύναμιν; τὸ μὲν οὖν ἀνάρρινον διὰ τὸ θερμότερον εἶναι ξηραντικώτερόν ἐστι τῆς γινομένης ὑπ' αὐτοῦ συντήξεως, ἐπεὶ ποιεῖ γε δάκρυον ἐσθίοντι· προσφερόμενον δὲ οὔ, ὅτι οὐκ ἀπατμίζει ἀπ' αὐτοῦ λεπτόν τι· ξηρότερον γάρ ἐστι καὶ θερμότερον. ἡ δὲ ὀρίγανος καὶ τὰ τοιαῦτα θερμὰ ξηρά ἐστιν ἠρέμα. δεῖ δὲ τὸ μέλλον δάκρυον ποιήσειν δηκτικὸν καὶ ὑγρὸν εἶναι καὶ γλίσχρον. διὸ καὶ τὸ ἔλαιον ποιεῖ δακρύειν, ἀσθενῆ ἔχον δῆξιν· διὰ γλισχρότητα γὰρ καὶ λεπτότητα παραδῦνον ποιεῖ τὸν πόνον, καὶ τὴν σύντηξιν διὰ τὸν πόνον. τὸ δὲ κρόμμυον τοιαύτην ἔχει τὴν δύναμιν ὥστε καὶ τὸ ὑγρὸν καὶ τὴν ἀτμίδα αὐτοῦ θερμὴν καὶ λεπτὴν καὶ γλίσχραν εἶναι. ὥστε προσφερόμενον μέν, διὰ τὸ τὴν ἀτμίδα τοιαύτην εἶναι καὶ συναφιέναι ὑγρότητα λεπτήν, ποιεῖ δακρύειν, ἐσθιομένου δὲ ἡ ἀναθυμίασις διιοῦσα ... τὸ δὲ σκόροδον θερμὸν μὲν καὶ δριμύ ἐστι καὶ ὑγρότητα ἔχει, ἀλλ' οὐ γλίσχρον· διὸ οὐ ποιεῖ δακρύειν.

Pseudo-Aristotle, Problemata, 21.22, 925a27-925b12

Alexis on knowing frivolous things.

"You don’t know what you're talking about. Run over and have a conversation with Plato and become enlightened about soda and onions."

λέγεις περὶ ὧν οὐκ οἶσθα· συγγενοῦ τρέχων
Πλάτωνι καὶ γνώσῃ λίτρον καὶ κρόμμυον.

Alexis, Ancylion ap. Diogenes Laertius, Vita philosophorum, 3.37