So, Diogenes Laertius says:
QuoteDisplay MoreHermippus relates that he entered a bronze bath of lukewarm water and asked for unmixed wine, [16] which he swallowed, and then, having bidden his friends remember his doctrines, breathed his last.
Here is something of my own about him29 :
Farewell, my friends ; the truths I taught hold fast :
Thus Epicurus spake, and breathed his last.
He sat in a warm bath and neat wine quaff'd,
And straightway found chill death in that same draught.
Such was the life of the sage and such his end.
29 Anth. Pal. vii. 106.
ὅτε καί φησιν Ἕρμιππος ἐμβάντα αὐτὸν εἰς πύελον χαλκῆν κεκραμένην ὕδατι θερμῷ καὶ αἰτήσαντα ἄκρατον ῥοφῆσαι:
16 [16] τοῖς τε φίλοις παραγγείλαντα τῶν δογμάτων μεμνῆσθαι, οὕτω τελευτῆσαι.
Καὶ ἔστιν ἡμῶν εἰς αὐτὸν οὕτω:
χαίρετε, καὶ μέμνησθε τὰ δόγματα: τοῦτ᾽ Ἐπίκουρος
ὕστατον εἶπε φίλοις τοὔπος ἀποφθίμενος:
θερμὴν ἐς πύελον γὰρ ἐληλύθεεν καὶ ἄκρατον ἔσπασεν, εἶτ᾽ Ἀΐδην ψυχρὸν ἐπεσπάσατο.
οὗτος μὲν ὁ βίος τἀνδρός, ἥδε <δὲ> ἡ τελευτή.
ἄκρατος pure, undiluted (strong) wine
Henry George Liddell, Robert Scott, A Greek-English Lexicon, ἄκρα_τος
I always saw this as more palliative for the pain than any hint of suicide. Ancient Greeks typically watered their wine down in a krater to drink. Drinking undiluted wine would have been noteworthy.
To me, this just points to the fact that one does everything to ease one's pain, but his drinking it and then dying seems to me that he was trying to eliminate pain from the disease/condition that was killing him and that he was on the verge of death already. I'd have to see evidence other than this text to convince me it was a suicide. And not Diogenes' poem. That was written hundreds of years after Epicurus's death.