Any and all displays of affection shown towards Poka physically and mentally hurts her in varying degrees. The kinder the interaction, the more pain lances. Sakura refrained from loving Poka partly because of Poka's weird illness
Though the pain is unbearable when shown too much affection, with blood leaking out, Poka sometimes thinks to herself that she can tolerate the pain if it means receiving some sort of love.
Hedgehog syndrome is incurable. Poka will always suffer from Hedgehog syndrome