Based on NIH | Can I drink a glass of milk at night while taking warfarin, or will it interfere with the medication or my INR?

You can generally drink a glass of milk at night while taking warfarin, as dairy products are low in vitamin K and are not known to meaningfully change INR in adults when consumed consistently. The key is to keep your diet steady from day to day so your warfarin dose remains appropriate. ^{[1] [2]}

How warfarin and diet interact

• Warfarin works by blocking vitamin K’s role in clotting; large or sudden changes in vitamin K intake can make warfarin less effective and lower your INR. Green leafy vegetables and certain vegetable oils are the main foods with high vitamin K that can blunt warfarin’s effect. ^{[1] [2]}
• Guidance for people on warfarin emphasizes a “consistent intake” of vitamin K rather than avoidance of all sources. Keeping your usual pattern of eating helps keep your INR stable. ^{[3] [4]}

Where milk fits in

• Ordinary cow’s milk and most dairy products are naturally low in vitamin K compared with leafy greens and do not appear on standard lists of foods that significantly interfere with warfarin. There is no established, clinically meaningful interaction between typical adult milk intake and warfarin anticoagulation when the diet is consistent. ^{[5] [6]}
• In specialized contexts (infants on vitamin K–enriched formulas), higher vitamin K in the formula can make warfarin less effective in pediatric patients, while exclusively human milk–fed infants may be more sensitive; this pediatric note does not apply to adults drinking milk. ^{[7] [8]}

Practical guidance for drinking milk on warfarin

• If you already drink milk (for example, 1 cup nightly), it’s reasonable to continue at about the same amount and timing. Avoid making sudden, large changes in your usual dairy intake without planning INR checks. ^{[3] [4]}
• If you plan to start or stop regular milk consumption (or switch to fortified products), let your anticoagulation clinic know so they can decide if earlier INR monitoring is needed. This is the same advice given for any routine diet change on warfarin. ^{[1] [2]}

Other diet and beverage reminders

• The most common dietary items that affect warfarin are high–vitamin K greens (spinach, kale, collards), some oils (soybean/canola), and certain botanicals or supplements; keeping intake steady helps avoid INR swings. ^{[1] [2]}
• Alcohol, grapefruit, green tea, and some herbs/supplements can also affect INR or bleeding risk; check with your care team before adding new supplements or making major changes. ^{[4] [9]}

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Quick reference table

Item	Vitamin K relevance	Typical guidance on warfarin	Notes
Milk (1 cup)	Low vitamin K	Generally acceptable if intake is consistent	No adult-specific interaction shown with stable intake [5] [6]
Leafy greens (spinach, kale, collards)	High vitamin K	Keep intake consistent; avoid large increases	Can lower INR and warfarin effect [1] [2]
Vegetable oils (soybean, canola)	Can be high in vitamin K	Use consistently; avoid sudden increases	May lower INR if intake rises significantly [1] [2]
Supplements/herbals	Variable	Consult care team; monitor INR with changes	Some can raise or lower INR or bleeding risk [9] [10]

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Bottom line

A nightly glass of milk is usually fine with warfarin as long as your overall diet remains consistent. Inform your healthcare team if you make significant, lasting changes to dairy or other vitamin K–containing foods so they can decide whether to check your INR sooner. ^{[1] [2]}