Motion sickness is an aliment caused by a disagreement with how the body visually perceives movement and how the inner ear senses it. Motion sickness often causes dizziness, fatigue, and nausea, and can lead to vomiting in extreme cases. A magical variant of motion sickness is Portkey-sickness, which specifically triggers upon travel by Portkey.
Madam Marsh suffered from a severe case of motion sickness. Despite this, for whatever reason, she was a frequent traveller on the Knight Bus, and often suffered greatly during the journey to her destination. Rubeus Hagrid suffered from a milder case of motion sickness when he travelled on the Mine Carts in Gringotts with Harry Potter in order to retrieve Harry's money and the Philosophers Stone. He still appeared slightly queasy after the trip, which resulted in him going to the Leaky Cauldron to recover while Harry went to buy his robes from Madam Malkin's shop.
- Harry Potter and the Philosopher's Stone (First appearance)
- Harry Potter and the Philosopher's Stone (video game) (Mentioned only)
- Harry Potter and the Prisoner of Azkaban
- Harry Potter and the Order of the Phoenix
- Pottermore (Mentioned only)