You may not drink coffee while fasting for Yom Kippur according to standard Jewish law; the fast prohibits all food and drink from sunset to nightfall the next day, including water and black coffee.

Core rule for Yom Kippur

  • Yom Kippur is a 25ā€‘hour total fast in mainstream halacha: no eating, no drinking at all, even plain water.
  • Because of that, any form of coffee (black, with sugar, with milk, iced, etc.) is considered drinking and is not allowed during the fast hours.

Why coffee feels confusing

A lot of online health and diet discussions say black coffee is okay for ā€œfasting,ā€ but they are talking about intermittent fasting or medical fasts, not religious fasts like Yom Kippur.

Some religious fasts (for example certain Catholic fasts) do allow black coffee, which adds to the confusion, but Yom Kippur is explicitly stricter: all food and drink are forbidden.

Preparing if you are a coffee drinker

  • Health and campus guides for Yom Kippur recommend reducing caffeine in the days before the fast so you do not get a withdrawal headache during the fast.
  • They also warn against ā€œloading upā€ on coffee right before the fast, since caffeine is a diuretic and can make you lose more water and feel worse as the fast goes on.

What if you have medical needs?

  • If you have conditions like diabetes, pregnancy, certain chronic illnesses, or medications that truly require fluids or caffeine, halachic and medical sources say you should speak both to a doctor and a competent rabbi.
  • In some cases, a person may be told to drink in small measured amounts (shiurim) or to take caffeine in pill form rather than as a drink, in order to reduce the halachic issue while protecting health.

Forum and ā€œrealā€‘lifeā€ practice

  • Jewish community health and guidance pages consistently describe Yom Kippur as a complete fast from all eating and drinking, without exception for coffee.
  • Online Jewish forums echo this: people may joke about ā€œneeding coffee,ā€ but the serious answers state clearly that Yom Kippur prohibits drinking, including coffee, and suggest preparation or alternative caffeine methods when necessary under rabbinic guidance.

Bottom line: For a regular, healthy adult observing Yom Kippur, you cannot drink coffee while fasting. If you have health concerns, this is one of those cases where you should ask both your doctor and a rabbi in advance.

Information gathered from public forums or data available on the internet and portrayed here.