This disease occurs when an empress falls in love with a man. If they suppress their emotions, it weakens them and causes extreme pain. Their health continues to decline and eventually leads to their death. This disease has killed many Kuja empresses in the past. It is unknown if the illness can be contracted by normal Kuja citizens.
In order to cure the disease, the empresses must accept their emotions and follow the loved one. This means that leaving Amazon Lily seems to be a prerequisite for the survival of the recipient, since the former Empress Gloriosa is currently the only known survivor, and was known to have left the island at some point prior to returning. She also implied that if Hancock, another sufferer of the disease, follows her beloved Luffy (which means leaving the island), she would not die. Outside of this cure, it is unknown if this disease can be cured by other means or if there is a cure specifically intended for it.
- Many empresses of the past have died because of their suppressed emotions.
- Elder Nyon has somehow survived the illness after falling in love with a man, even though their relationship is unknown.
- Boa Hancock, having fallen in love with Monkey D. Luffy, contracted the disease. However, she managed to hold it off when she accepted her feelings and decided to leave the island with Luffy. Slight symptoms have resurfaced, such as barely eating or sleeping while she was unsure of Luffy's condition, so she is most likely not cured. Sometime later, she collapsed when her heart started pounding faster. When she finally parted ways with Luffy, she asked him not to say the word "goodbye", but mistook Luffy's word of meeting again as proposal for marriage.
|— Elder Nyon on Love Sickness|
The disease basically develops as an exceptionally extreme version of the emotions that lovers would suffer while courting each other. The disease seems to be a psychosomatic illness.
According to Elder Nyon, the feelings of emotion are "like a hurricane" hitting when least expected. The victim suffers unbearable pain in their heart when their love attempts to leave the island and even mentioning the date of leaving is enough to cause agony. However, when their love is present, the victim may display usual strength when needed be, or possibly be rendered powerless. As seen with Hancock, they can become a completely different person, possibly even blinded by their love for the person so much that they do not acknowledge anyone else around them (or even their love for that matter, as Hancock demonstrated). No one matters more to them and every action their love does is interpreted incorrectly by the sufferer.
- The term "love is a hurricane", was actually first used by Sanji back in the Arlong Park Arc. In fact, Nyon reveals it to be an East Blue original dictum.
- One Piece Manga and Anime — Vol. 53 Chapter 522 (p. 17) and Episode 417, Elder Nyon explains about Love Sickness.
- One Piece Manga and Anime — Vol. 54 Chapter 523 (p. 3) and Episode 417, Nyon advises Hancock to go with Luffy.
- One Piece Manga and Anime — Vol. 59 Chapter 582 (p. 6) and Episode 491, Hancock not yet cured of her Love Sickness.
- One Piece Manga and Anime — Vol. 60 Chapter 594 (p. 15) and Episode 512, A Kuja stated that Hancock collapsed when her heart was pounding so much.
- One Piece Manga — Vol. 9 Chapter 76, Sanji says to Zoro that love is like a hurricane.
- Love Sickness - A Wikipedia article on love sickness.
- Broken heart syndrome - A Wikipedia article on broken heart syndrome