Answer:
Niacin
Step-by-step explanation:
Niacin which is a form of vitamin B3 is one of the eight B-complex water-soluble vitamins. Niacin, which is an important nutrient that performs various vital functions in the body, occurs naturally in some of the food we consume, such as poultry, eggs, fish, milk, cereal grains. Niacin can also be taken as a supplement and can be used to lower cholesterol.
Niacin, when taken at large doses causes side effects such as severe facial flushing and liver damage. Niacin when taken at larger doses is said to cause dilation of the small blood vessels in the skin which results in the rush flow of blood.
Apparently, Felicity most likely took vitamin B3 which is niacin, as a supplement.