Sawm/ Roza/ Fasting is obligatory in Shia Islam, in ninth month ‘Ramadan’ of Lunar Islamic Calendar (Hijri). Sawm/ Roza/ Fasting is second in the 'Furu Deen' or Branches of Faith. A very special night, mentioned in Holy Qur'an as 'Laylatul Qadr' occurs in Ramadan.
Fasting is obligatory in Shia Islam on sane adult Shia Muslims both men and women. However, there are people on whom fasting is not obligatory. A Musafir/ Traveller who must Qasr/ shorten his Salah/ Namaz/ Prayers cannot fast. Old age people to whom fasting causes extreme hardship are exempted from fasting. Any other person is also exempted from fasting to whom it causes extreme hardship. Any person who suffers from a disease which causes Polydipsia (suffer from excessive thirst) or under extreme hardship is exempted from fasting. Pregnant ladies are exempted from fasting. Suckling mothers whether biological mothers or suckling mothers are exempted from fasting.
Shia Muslims are required to fast from dawn, when the whiteness in the sky starts to spread (before sunrise) and continue to till redness after sunset passes the top. Holy Qur’an ask us to fast from Fajr/ Dawn up to Layl/ Night, Holy Quran did not used the word Maghrib/ Sunset as time to end the fast rather asks us to continue fasting till Night/ Layl.
The difference between Shia and Sunni Sawm/Roza/ Fasting is that Sunni end the fast with Maghrib/ Sunset, while Shia Muslims continue the fast till the Night/Layl approaches, which differ from place to place.
Niyyah/Intention is required in Shia Islam for fasting. Without Niyyah/ Intention fasting is void. In Shia Islam Niyyah/ Intention is intention in mind, thus one is not required to say it with mouth, just intending in mind is enough. Also, one is not required to make daily intentions during month of Ramadan, if one intends to fast the whole month right at the start of month, it will suffice. There will be no problem if person doesn’t observe all fasts with that Niyyah/ Intention. Taharah/ Spiritual Purity is required in Shia Islam, this is major difference between Shia Islam and other sects.
There are some Non-Shia, who preach fasting as alternate dieting. They say best dieting is fasting. If you fast you will have double benefit it will help you in dieting and also earn you divine rewards of fasting. This concept is ridiculous and stupid in Shia Islam, because intention in Shia Islam should be solely worship of Allah (God), the moment any other intention joins it like dieting etc, fasting will become null and void in Shia Islam. Thus in Shia Islam Sawm/ Roza/ Fasting is solely worship of Allah (God), for a Shia Muslim he/she is free to diet for whole other eleven months of year but when a Shia Muslim must fast in month of Ramadan etc, that is solely worship of Allah (God).
During Fasting Shia Muslim are required not to indulge into any of these nine things or acts. The person who fasts cannot eat or drink. The person who fasts cannot have sexual intercourse (mere penetration). The person who fasts cannot voluntarily ejaculate (Masturbate leading to ejaculation). The person who fasts cannot attribute any lie (false things) to Allah (God), Prophet Mohammed or Twelve Imams (Aimmah). The person who fast cannot inhale or swallow thick dust in throat (ie: smoking cigarette). The person who fasts cannot immerse his/her entire head in water. Remaining Najis/ Spiritually Impure till the time of Fajr/ Dawn prayer. The person who fasts cannot use liquid enema. Vomiting by a person who is fasting makes his/her fast void. Doing any of these things or if any of these things happens the fast will break.
In Shia Islam, swallowing one’s saliva, salivating at smell of food, involuntary ejaculation (nocturnal emissions), pre-cum, erections in men etc doesn’t break one’s fast.
There are things which one does or happens that does not break Sawm/ Roza/ Fast in Shia Islam. Although these thing won’t break fast but are not preferred in fasting and must be avoided. The person who fasts should not use eye drops or cosmetic eye stuffs, if its taste or smell is felt inside. The person who fasts should not perform an act which causes excessive weakness, should not extract blood, or have hot bath etc. The person who fast should not snuff when one is sure it might reach throat. The person who fasts should not use stimulants for bowels. The woman who fasts should not sit immersed in water. The person who fasts should not wet one’s dress which one is wearing. The person who fast should not extract tooth or allow any other action causing bleeding in mouth. A person should not use a wet toothbrush, in Shia Islam one cannot use Miswak/ Siwak (thin branches or thin root of several trees used as tooth brush) while one is fasting, this is a major difference between Shia and Sunni. The person who fasts should not put water or any other liquid in mouth without an appropriate cause (ie: gargle). The person who fasts should not indulge in foreplay, romance, kissing etc with one’s partner without the intention of ejaculation, if intention is there fast as a precaution would be considered broken.
Suhur/ Sehri/ Pre-fast meal is a meal which is taken before commencing the fast, it is taken in such a manner that by the time one finishes the meal, Fajr/ Dawn, the time for commencing the fast should begin. Suhur/ Sehri/ Pre-fast meal is recommended to be eaten in last part of night, like a morning breakfast. It is not a compulsive meal but highly recommended; at least a date and water will suffice.
When Layl/ Night approaches, it is recommended to formally end the fast by date, water, salt, fruits etc. This post-fast meal is called Iftar. Iftar/ post-fast meal is recommended not to be delayed on the Layl/Night has arrived.
Both Suhur/ Sehri/ pre-fast meal and Iftar/ post-fast meal are Sunnah/ Traditions of Prophet Mohammed and are highly recommended. One is free to eat, drink, have sexual intercourse and any other legal activity forbidden during fast.
If anyone is not observing fast due to several conditions, or the fasting person breaks the fast in middle with eating, drinking or sexual intercourse etc, the person must offer Kaffarah/Compensation (ie: feeding poor), observe Qadha Fast/ Observe pending fast or both depending on conditions which varies from situation to situation, details are lengthy and thus, avoided here, as this is just a brief information.
Apart from Obligatory fasts of Ramadan, there are other preferred fasts in Shia Islam on other special days also; their details are available in Shia religious books/sites. A married woman is required to take permission of her husband for such preferred fasts. One is required to take permission of one’s father before observing such fasts, whether one is independent or not, son or daughter, except in case of married ladies. It is forbidden to observe such fasts if it causes emotional suffering to parents.
There are several days when fasting is Haram/ Forbidden or Makrooh/ Disliked in Shia Islam. The day of Eid al Fitr, Eid al Adha. A major difference between Shia and Sunni is that Shia don’t fast on Ashura (10th Moharram) while Sunni do fast on that day. Ashura (10th Moharram) is the day tragedy of Karbala (Iraq) happened, and for Shia Muslims it is a day of sorrow and mourning.
The content on Sawm/ Roza/ Fasting in Shia Islam over here is brief explanation; details could be had from further reliable sources.
O Allah! Peace and Salutation be upon Mohammed and House-hold of Mohammed.