Thiruvathira is a day of fasting and the women discard the ordinary rice meal on that day, but only take preparations of chama (panicum miliaceum) or wheat. Other items of their food include plantain fruits, tender coconuts, etc. They also chew betel and redden their lips. Among Namboodiris, Ambalavasis (temple-servants) and high class Nairs, there is a convention that each woman should chew 108 betels on that day. The first Thiruvathira coming after the marriage of a girl is known as Puthen Thiruvathira or Poothiruvathira and it is celebrated on a grand scale.

From prehistoric times, the Malayalee women enjoyed an enviable position in the society, and she was practically the mistress of her house. The elevated position she occupied at home and in the society had distinguished her from her neighbours and influenced to a considerable extent the social structure, customs and religious practices of the people. The culmination of this phenomenon is clearly visible in setting apart one of the three great festivals of Kerala. viz. Thiruvathira, exclusively for womenfolk, for which a parallel can hardly be found in any section of the Indian Society.

Oonjalattom, (swinging on an oonjal (swing) is an item of amusement on this occasion. At night, the women keep vigil for Shiva and perform Thiruvathirakali or Kaikottikali. They stand in a circle around a lighted brass lamp, and dance each step to the rhythm of the songs they sing, clapping their hands. The songs sometimes consist of Kathakali songs including the works of Irayimman Thampi.

Among Namboodiris and Ambalavasis (temple servants) and Nairs who have close association with Namboodiris, there is a custom called Pathirappoochoodal, meaning wearing of flowers at midnight. At the midnight of Thiruvathira, an image of Shiva is placed at the central courtyard and flowers, plantains and jaggery are offered to the deity. They then perform Kaikottikali round the deity. Flowers are taken from the offering and worn by them.