The Core Rule: 'The Jawf'
In Fiqh, a fast is generally broken if a substance enters
the Jawf (body cavity/stomach) through a valid
passageway (Mouth, Nose, etc.) intentionally.
Key distinction: Is the substance nutritious (like food/drink) or is it a non-nutritious medical aid? This
is where many modern scholars (differing from classical texts)
validate things like injections.
Medical Procedures Matrix
Modern medicine involves many entry points to the body. Here is a summary of the consensus on common procedures:
Hygiene & Self Care
Can I brush my teeth?
Yes. However, it is Makruh (disliked) to use toothpaste
because of the strong taste and risk of swallowing. If you are careful
and spit it all out, your fast is valid.
Recommendation: Use a Miswak or brush dry.
Can I use perfume/bukhoor?
Yes. Smelling pleasant scents does not break the fast. However, intentionally inhaling thick smoke (like Bukhoor incense) directly into the nose/throat is prohibited by many scholars as the smoke particles have 'body'.
Does swimming break the fast?
No, but it is risky. If water enters the ears, it is fine (as the ear canal doesn't connect to the throat unless the drum is perforated). However, if water enters via nose or mouth and is swallowed, the fast is broken.
Accidental vs Intentional
The Prophet (ﷺ) said: "Whoever forgets he is fasting and eats or drinks, let him complete his fast for it is Allah who has fed him and given him drink." (Bukhari)
This forgiveness applies strictly to forgetfulness. If you remember halfway through swallowing, you must stop immediately.