Short answer
It does not affect the marriage: nursing creates a mahram bond only in the first two years of life. But in the Hanafi school a husband should not deliberately drink his wife's milk, since human milk is not for an adult's use. Kissing and touching the breasts in intimacy is fine, and swallowing a little by accident is not a sin. The Shafi'i school is more lenient.
Drinking a woman's milk after the nursing period is not permissible, because human milk is part of a person and may only be used for need, as for an infant. It creates no foster relationship for an adult, so the nikah is unaffected. Touching and kissing the breasts in intimacy is permitted, and milk swallowed unintentionally carries no sin.
Other madhhabs
- Shafi'i
- Human milk is pure and lawful to drink, so a husband who drinks it does not sin.
Explanation
People ask two separate things here: whether it affects the marriage, and whether it is allowed.
The marriage is not affected. Nursing (rada') creates a mahram relationship only when the child is of nursing age, which Allah sets at two complete years (2:233). That is the relied-upon Hanafi fatwa, following Abu Yusuf and Muhammad, while Abu Hanifa held two and a half years. The Prophet ﷺ said that the nursing which counts is the one that satisfies hunger, meaning an infant's. An adult husband does not become his wife's foster son. See nursing and mahrams.
Is it allowed? In the Hanafi school, deliberately drinking it is not, because human milk is part of the human body and its use is allowed only for need. In intimacy, touching and kissing the breasts is permitted. If some milk enters the mouth, it is better to spit it out, and anything swallowed by accident is forgiven. The Shafi'is consider human milk pure and lawful to drink, so they see no sin in it.
While a baby is nursing, the baby has the first right to the milk, so nothing should reduce the child's supply. On the few things that are forbidden between spouses, see what is forbidden in intimacy.
The evidence
Quran, Surah Al-Baqara 2:233
۞ وَٱلْوَٰلِدَٰتُ يُرْضِعْنَ أَوْلَٰدَهُنَّ حَوْلَيْنِ كَامِلَيْنِ ۖ لِمَنْ أَرَادَ أَن يُتِمَّ ٱلرَّضَاعَةَ ۚ وَعَلَى ٱلْمَوْلُودِ لَهُۥ رِزْقُهُنَّ وَكِسْوَتُهُنَّ بِٱلْمَعْرُوفِ ۚ لَا تُكَلَّفُ نَفْسٌ إِلَّا وُسْعَهَا ۚ لَا تُضَآرَّ وَٰلِدَةٌۢ بِوَلَدِهَا وَلَا مَوْلُودٌۭ لَّهُۥ بِوَلَدِهِۦ ۚ وَعَلَى ٱلْوَارِثِ مِثْلُ ذَٰلِكَ ۗ فَإِنْ أَرَادَا فِصَالًا عَن تَرَاضٍۢ مِّنْهُمَا وَتَشَاوُرٍۢ فَلَا جُنَاحَ عَلَيْهِمَا ۗ وَإِنْ أَرَدتُّمْ أَن تَسْتَرْضِعُوٓا۟ أَوْلَٰدَكُمْ فَلَا جُنَاحَ عَلَيْكُمْ إِذَا سَلَّمْتُم مَّآ ءَاتَيْتُم بِٱلْمَعْرُوفِ ۗ وَٱتَّقُوا۟ ٱللَّهَ وَٱعْلَمُوٓا۟ أَنَّ ٱللَّهَ بِمَا تَعْمَلُونَ بَصِيرٌۭ ﴿٢٣٣﴾
Mothers may breastfeed their children two complete years for whoever wishes to complete the nursing [period]. Upon the father is the mothers' provision and their clothing according to what is acceptable. No person is charged with more than his capacity. No mother should be harmed through her child, and no father through his child. And upon the [father's] heir is [a duty] like that [of the father]. And if they both desire weaning through mutual consent from both of them and consultation, there is no blame upon either of them. And if you wish to have your children nursed by a substitute, there is no blame upon you as long as you give payment according to what is acceptable. And fear Allah and know that Allah is Seeing of what you do.
The nursing period that creates foster ties is in infancy.
Sahih al-Bukhari 5102
Sahih... فإنما الرضاعة من المجاعة ...
"Nursing that counts is only that which satisfies hunger."
Only an infant's nursing creates a foster relationship.
Sahih al-Bukhari 2645
Sahih... يحرم من الرضاعة ما يحرم من النسب ...
"Nursing makes forbidden what lineage makes forbidden."
Explains what a valid nursing relationship does, which an adult's drinking does not.
Where the ruling is recorded
- al-Hidaya, Kitab al-Rada'. The nursing period, two and a half years for Abu Hanifa and two years for his two companions.
- Radd al-Muhtar (Ibn Abidin), Kitab al-Rada'. Benefiting from human milk after the nursing period is not permitted.
- al-Majmu' (Nawawi), Kitab al-Taharah, on what is pure. The Shafi'i view that human milk is pure and lawful.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.