Sayyed Mohammad Al-Musawi, Sayyed Mohammad al-Musawi is originally from Iraq and heads up the World Ahlul Bayt Islamic League in London. Other than being involved in various humanitarian projects, he frequently responds to... Answered 1 month ago

It does not break the fast no matter how bad it is. Fast breaks only in commuting any of the nine Mufattiraat ( fasting invalidating acts)e.g. Eating, drinking, smoking, lying on Allah or on The Infallible etc.

Many sinful acts do not invalidate fast despite the fact that they are sinful.