Sherry Haynes is currently pursuing a PharmD degree and has experience in both the clinical and management sides of pharmacy.
One of the most asked questions by patients is whether or not to take the meds with milk. The answer to this question depends on what exactly the medicine composition is. There are some medicines that should not be taken with milk. The reason for this is that milk interacts with them making them fail to work. When the term 'milk' is mentioned, most times not only is it milk that should be avoided but all the other dairy products like yogurt, cottage cheese, buttermilk and supplements containing calcium, magnesium, iron, and zinc.
When the presence of milk, food, herbs, or other drugs affect the action of a drug, it is called “interaction”. Drug-food interactions can cause changes in the proportion of drug entering the circulation. This can influence the safety and efficacy of drug therapy and may lead to treatment failure and in some cases, this may also result in beneficial effects.
The drug-milk interactions are usually moderate in severity as they cause a failure in the treatment and you may need an additional treatment.
How do milk and other dairy products affect the action of medicines?
Some antibacterials e.g. tetracyclines can chelate with calcium present in the milk and other dairy products to form insoluble complexes that are poorly absorbed and have reduced antibacterial effects.
The same mechanism of interaction goes for magnesium, aluminium, bismuth, zinc, and iron present in many supplements and antacids. Most tetracyclines and related drugs come with a warning on the label to avoid milk and dairy products. The patients may often not realize that antacids, laxatives, and nutritional supplements should be shunned too. Many female patients take calcium pills to prevent osteoporosis. Most may also be taking vitamin and mineral supplements with iron, magnesium, and zinc.
These type of interactions might not sound very serious but dangerous situation could occur if a patient had rocky mountain spotted fever. This disease can be fatal if it is not treated quickly with antibiotic preferably tetracycline. Inactivation of this antibiotic by vitamin and mineral supplements could lead to tragedy.
Milk is also to be avoided with laxatives containing bisacodyl. The coating on such meds is done with an intention to prevent their dissolution into the stomach which has an acidic environment. The coating on these pills help the drug dissolve only when it reached the intestine. When you take milk with the drug it lowers the stomach acidity and causes the drug to dissolve there instead of in the intestine, causing irritation in the stomach and hard stomach ache.
Separating the dosages of such medicines and antacids or calcium supplements by 2 to 3 hours goes some way towards reducing the effects of this type of interaction.
Drugs That Should Not Be Taken With Milk
1. Tetracycline and Teracycline-like antibiotics
Tetracycline antibiotics are broad-spectrum antibiotics that act by inhibiting the growth of bacteria. These are used for a large number of purposes from the treatment of acne to malaria, brucellosis, chlamydia infection, and Lyme disease.
Tetracycline can bind to calcium and iron present in the milk, forming insoluble chelates, and reducing its level in the circulation. Milk can reduce the blood levels of tetracycline drugs by 50% or more. This much decrease in the bioavailability is enough to sabotage their impact.
Interestingly, orange juice and coffee also contain calcium but do not interact with tetracyclines.
Tetracyclines include demeclocycline, methacycline, tetracycline, doxycycline, ocytetracycline, minocycline.
2. Quinolones - Ciprofloxacin, Norfloxacin, Gatifloxacin
Quinolones are other broad-spectrum antibiotics that act by killing the bacteria. These are often used for genitourinary infections such as pyelonephritis and sickle cell disease.
In the same way as in tetracycline antibiotics, calcium and caesium in milk and yoghurt or other dairy products combine with quinolone antibiotics to produce insoluble chelates.
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Ciprofloxacin, norfloxacin, and gatifloxacin show reduced bioavailability when taken with milk. Whereas, xenoxacin, lomefloxacin, moxifloxacin, ofloxacin, and flevoxacin do not show such interaction.
In a study, the peak levels of oral Phenoxymethylpenicillin and oral Benzyl penicillin were reduced by 40-50% in children when they were given with milk. So, it is recommended that phenoxymethylpenicillin is taken 1 hour before food or on empty stomach to optimise the absorption. Due to poor oral absorption benzylpenicillin is given intramuscularly or intravenously which would be administered in the hospital.
4. Etidronate, Alendronate
Etidronate is a class of drug called bisphosphonates, prescribed for treating osteoporosis and bone pain from diseases such as metastatic breast cancer and Paget's disease. But, if calcium is consumed within 2 hours of taking the drug, it will be absorbed inadequately.
Laxatives are substances that loosen stools. Milk interferes with the action of laxatives containing bisacodyl (Dulcolax). Normally laxatives containing bisacodyl are enteric-coated i.e., coating done to keep them from dissolving in the acid environment of the stomach so that they go to work in the lower region of the intestine. Drinking milk at the time of taking tablet may lower the stomach acidity enough that the coating dissolves there. This could result in stomach irritation and very bad belly ache.
Fleicainide is an anti-arrhythmic drug. It is used to restore normal heart rhythm and maintain a regular, steady heartbeat. It is also used to prevent certain types of an irregular heartbeat from returning (such as atrial fibrillation).
In infants, the absorption of flecainide is reduced by milk.
7. Non-steroidal Anti-inflammatory Drugs (NSAIDS) - Nabumetome, Ketoprofen
NSAIDS are drugs prescribed to reduce fever, pain, and inflammation. These are the most common drugs used. NSAIDs like ibuprofen, naproxen, and others can cause stomach irritation and thus they should be taken with food or milk.
However, there are two drugs that show minor interaction with milk. Absorption of ketoprofen is reduced by milk. Whereas the absorption of another NSAID, Nabumetone is increased due to milk.
It is used to treat Wilson's disease, a genetic metabolic defect that causes excess copper to build up in the body.
The drug should be taken 1 hour apart from milk. On theoritical grounds, Trientine can chelate with iron decreasing its absorption.
It is an antidepressant drug, prescribed to treat mood and anxiety disorders. Very large amount of milk (as much as 1 litre) can cause 40% reduction in the absorption of paroxetine.
10. Strontium ranelate
Dairy products, Calcium compounds such as calcium containing antacids can cause marked decrease in the absorption of strontium ranelate. It is recommended to separate the administration of drug by at least 2 hours.
Ritonavir is used in the treatment of HIV/AIDS. Milk and dairy products can increase the absorption of ritonavir by 13%.
Mercaptopurine is used for cancers (acute lymphoblatic leukemia and chronic myelogenous leukemias). It is inactivated by an enzyme called xanthine oxidase (XO). Concurrent intake of substances containing XO may potentially reduce bioavailthe ability of mercaptopurine. Cow's milk is known to contain a high level of XO which ay reduce the bioavailability of mercaptopurine. This interaction may be clinically significant. Therefore most patients should try to separate the timing of taking mercaptopurine and drinking milk.
It is an anticancer drug. Its absorption is reduced by milk, food and supplements containing calcium.
Follow the following steps to avoid drug and milk interactions
- To avoid drug-milk interactions, take meds and milk at different times. Taking milk 2 or 3 hours before or after taking these meds is fine.
- Take medicines with a full glass of water.
- Read the prescription label on the container. If you do not understand something or think you need more information, ask your physician or pharmacist.
- Read directions, warnings and interaction precautions printed on all medication labels and package inserts. Even over-the-counter medications can cause problems.
- Make sure to follow all your doctor's dietary and medical instructions to make sure your treatment is working safely and effectively.
- Stockley, I. H., & Baxter, K. (2008). Stockley's drug interactions: A source book of interactions, their mechanisms, clinical importance, and management (8th ed.). London ; Chicago: Pharmaceutical Press.
- de Lemos ML, Hamata L, Jennings S, Leduc T. Interaction between mercaptopurine and milk. J Oncol Pharm Pract. 2007 Dec;13(4):237-40.
This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.
Questions & Answers
Question: Specifically, since milk contained saturated fats, and interfere with drug absorption, what about products like coconut water and meat? Can meat and coconut milk work against drug absorption?
Answer: Milk does interfere with drug absorption but not due to the high content of saturated fats. (Meaning even low-fat milk should be avoided for such drugs)
1. Milk contains divalent cations like calcium, iron, caesium that form chelates with antibiotics like tetracyclines and some quinolones and become insoluble so that they are not absorbed as efficiently.
2. Laxatives are enclosed in a capsule in such a way that they survive the acid environment of the stomach and release the medicine in the intestine. But, because milk decreases the acidity of the stomach the capsules release the medicine in the stomach itself causing irritation and stomach ache.
3. Xanthine oxidase is an enzyme that inactivates mercaptopurine (a drug used in certain types of cancers) and reduces its proportion in the blood circulation. It is present in milk at high levels so it is recommended to avoid milk while using this drug.
Meat has to be avoided for certain drugs because it contains a high amount of tyramine. Drugs that interact with tyramine include Linezolid (an antibiotic), antitubercular drugs (ethambutol, pyrazinamide, rifampin, isoniazid) and antidepressant drugs ( phenelzine, tranylcypromine).
I am not aware of any drug interacting with coconut water but since it lowers blood pressure, it is better to avoid it while taking medicines that lower blood pressure (your regular antihypertensive/ BP lowering meds).
© 2019 Sherry Haynes
Miebakagh Fiberesima from Port Harcourt, Rivers State, NIGERIA. on March 13, 2019:
Hello, Sherry, this is very informative. Thanks for sharing.