Islam is a religion of mercy and caters for all the problems faced by humanity. It acknowledges the needs of people, thus gives concessions and dispensations wherever needed. Hence, it can be said that blood transfusion is lawful as a necessity. "And if any one saved a life, it would be as if he saved the life of all mankind." (Al Quran: Surah Al-Ma'dah: 32)
1. The donor is mature and sane
2. The donor willingly donates his blood. If he is compelled to do so, it will not be permissible
3. There is no apparent risk to the life or health of the donor
4. There is no reasonable alternative
5. It is not for the sake of beatification or any other additional benefit
It is permissible to donate blood to non-Muslims as long as they are not fighters of Islam. A fighter of Islam would be defined as one who fights Muslims with weapons or finances such fighting with his wealth, or helps such fighting. If one is not able to know for sure, then it suffices to act according to ghalabat ul-zann (one's best estimate or what is most likely and probable).
It is not permissible to sell blood, because of the report in Saheeh al-Bukhaari from the hadeeth of Abu Hudhayfah, who said: "I saw my father buy a cupper [a person who does cupping] and order that his tools be broken. I asked him about that and he said, 'The Messenger of Allah (peace and blessings of Allaah be upon him) forbade the price of blood," (Al-Bukhaari, 3/12, 43; Ahmad, 4/308, 309). Al-Haafiz said in al-Fath: what is meant by the prohibition of blood is the same as the prohibition of dead meat and pork. It is haram according to scholarly consensus, i.e. selling blood and taking its price.
It is not recommended to donate blood while fasting unless there is an absolute necessity to do so. Drawing lots of blood may make a person weak and thus he may be forced to break his fast. So indulging in such an activity is not at all recommended as we are advised to keep our fasts intact as best as possible. Moreover, there are scholars who are of the opinion that drawing lots of blood would invalidate one's fast. This is the view of Imam Ahmad.
However, Imam Ash-Shafi'i and others are of the view that drawing of blood by itself does not break the fast, but one is not encouraged to do so as it may render a person weak. The ruling, however, is different when faced with an emergency. Such is the case when one must donate blood to save a person's life; in this case one must do so without any hesitation; it is better for him to break his fast if he has to than continuing his fast. Another exception: If a person is exceptionally strong and is certain that donating blood would not render him weak at all, then there is no harm for him in donating blood, according to the view of Imam Ash-Shafi'i and others. In conclusion: Each person should consider his own state of health before embarking on this action.
Most people can give blood. If you are generally in good health, age 17 to 65 and weigh at least 50kg (7st 12lb) you can donate. For a more detailed list of who can/can't give blood, please click here.
Male donors can give blood every 12 weeks, while female donors can give every 16 weeks.
This is an issue concerning which the scholars, may Allah have mercy on them, differed. Those who think that bleeding breaks wudoo' quote as evidence the hadeeth of Abu'l-Darda' (may Allah be pleased with him): "The Prophet (pbuh) vomited, then did wudu." They drew an analogy between vomit and blood, because both are naajis (impure) when they come out of the body.
This hadith was narrated by Ahmad (4/449), Abu Dawood (2981) and al-Tirmidhi (87), who said: "More than one of the scholars among the Companions of the Prophet (pbuh) and others among the Taabi'een thought that wudu should be done after vomiting or having a nose-bleed. This is the opinion of Sufyaan al-Thawri, Ibn al-Mubaarak, Ahmad and Ishaaq. Some scholars said that wudu is not necessary after vomiting or having a nosebleed. This is the opinion of Maalik and al-Shaafa'i." This was also narrated as being the opinion of Ahmad. Al-Baghawi said: It is the opinion of most of the Sahaabah and Taabi'een."
The most correct view is that bleeding does not break one's wudu, although it is preferable (mustahabb) to make wudu after bleeding. The evidence for this is as follows:
Wudu is considered to be valid until there is proof that something breaks it. There is no proof narrated from the Prophet (pbuh) that bleeding breaks wudu, hence Imaam al-Nawawi (may Allah have mercy on him) said, "There is no proof whatsoever that the Prophet (pbuh) made it obligatory to do wudu because of that (bleeding)." Shaykh Ibn Sa'di (may Allaah have mercy on him) said, the correct opinion is that bleeding and vomiting, etc., do not break wudu, whether they are large or small in volume, because there is no evidence to proof that they break wudu, and the guiding principle is that wudu remains valid.To sum up the above: It is mustahabb (preferable) for a blood donor to do wudu after giving blood, but if he does not do wudu, it is still OK.