Short answer
Say bismillah before you drink, and after drinking milk say: Allahumma barik lana fihi wa zidna minhu (O Allah, bless it for us and give us more of it). The Prophet ﷺ taught this dua especially for milk. It is sunnah, not obligatory.
Saying bismillah before and alhamdulillah after any food or drink is sunnah, and this dua after milk is mustahabb (recommended). Rinsing the mouth after drinking milk is also mustahabb.
The four schools agree on this.
Explanation
The dua is اللهم بارك لنا فيه وزدنا منه: Allahumma barik lana fihi wa zidna minhu, "O Allah, bless it for us and give us more of it."
In the same hadith the Prophet ﷺ taught a dua after food in general: Allahumma barik lana fihi wa at'imna khayran minhu, "O Allah, bless it for us and feed us with better than it." For milk he asked for more of it rather than something better, and explained that nothing else serves as both food and drink the way milk does.
A simple way to follow the sunnah:
- Say bismillah before drinking.
- Drink sitting, with your right hand, in three breaths.
- After drinking, say the milk dua and alhamdulillah.
- Rinse your mouth. The Prophet ﷺ did this after milk and said that it leaves a fatty residue.
The four schools agree that these are recommended manners, not duties. If you have not memorised the Arabic, praise Allah in your own words until you learn it. If you forgot bismillah at the start, see what to say if you forgot bismillah. The general duas are on dua before eating and dua after eating.
The evidence
Quran, Surah An-Nahl 16:66
وَإِنَّ لَكُمْ فِى ٱلْأَنْعَٰمِ لَعِبْرَةًۭ ۖ نُّسْقِيكُم مِّمَّا فِى بُطُونِهِۦ مِنۢ بَيْنِ فَرْثٍۢ وَدَمٍۢ لَّبَنًا خَالِصًۭا سَآئِغًۭا لِّلشَّٰرِبِينَ ﴿٦٦﴾
And indeed, for you in grazing livestock is a lesson. We give you drink from what is in their bellies - between excretion and blood - pure milk, palatable to drinkers.
Milk is one of Allah's signs and blessings.
Jami' at-Tirmidhi 3455
Grading to be checked... اللهم بارك لنا فيه وزدنا منه ...
"When he is given milk to drink, let him say: O Allah, bless it for us and give us more of it."
The dua taught specifically for milk.
Sahih al-Bukhari 211
Sahih... إن له دسما ...
"It has fat in it."
He rinsed his mouth after drinking milk.
Where the ruling is recorded
- al-Fatawa al-Hindiyya, Kitab al-Karahiyya, chapter on eating and drinking. The manners of eating and drinking, including bismillah at the start and praising Allah at the end.
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.