Usually felt internationally in the two weeks succeeding the book's release.
Post Potter Depression (PPD) is an emotional state, and is generally inversely related to the Economic Post Potter Elation (EPPE) initially felt by Bloomsbury, Scholastic, and Raincoast Books, and felt soon thereafter by the world's retail booksellers.
Post Potter Depression may remain incurable for some, but many recover within a week of showing initial symptoms.
Most people, mainly parents, feel it is not a serious condition and will cure itself.
Some anti-depressants to Post-Potter Depression are watching A Very Potter Musical AVPM or A Very Potter Sequel AVPS, rereading the books or rewatching the movies, or curling up in the fetal position, drowning you sorrows with hard liquor, and praying for an acceptance-letter baring owl.
It is quite a tragedy to behold. During this period, and after, Twilight must be no where in the vicinity. The mockingness of the awful acting will send the sufferer into a deeper depression, restarting the cycle anew.
Denial: "No! It's not over! And...and Dumbledore isn't dead! Yes! Neither is Dobby!"
Pain: "Why? Why? Oh cruel J.K Rowling, giving us this gift then yanking it away so quickly!"
Anger: "I'm going to murder Hollywood! Grah! And you too, kitty!" "Meow?" (an innocent cat may die. R.I.P kitty.)
Depression: "I'LL NEVER GET OVER THIS! I'LL BE UNHAPPY FOREVER!!!
Acceptance: "You know, this actually isn't so bad. In fact, I--is that Robert Pattinson?"
(then back to Denial)