Can Medicines Be Taken With Milk or Other Dairy Products?
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 is. There are some medicines that should not be taken with milk the reason being, milk interacting 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 yoghurt, cottage cheese, butter milk and supplements containing calcium, magnesium, iron, and zinc.
When the presence of milk, food, herbs, or other drugs affects the action of a drug, it is called “interaction”. Drug-food interactions can cause changes in 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, beneficial effects.
The drug-milk interactions are mostly pharmacokinetic interactions, since the milk affects the absorption and excretion of drugs. These types of interactions are usually moderate in severity as they cause a failure in treatment and need for additional treatment.
How does milk or 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 other divalent and trivalent metallic ions, such as 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. It 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.
In other cases, such as in laxatives containing bisacodyl that are coated with an intention to prevent their dissolution into the acid environment of the stomach, and cause them to go to intestine to dissolve there for the intended action. Milk lowers the stomach acidity and causes the drug to dissolve there instead of intestine, causing irritation in the stomach and hard stomach ache.
Separating the dosages of the meds and antacids or calcium supplements by 2 to 3 hours goes some way towards reducing the effects of this type of interaction.
Here is a list of 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 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 bioavailability. 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.
Orange juice and coffee are calcium containing foods/drinks but do not interact with tetracyclines.
Tetracyclines include demeclocycline, methacycline, tetracycline, doxycycline, ocytetracycline, minocycline.
2. Quinolones - Ciprofloxacin, Norfloxacin, Gatifloxacin
Quinolones are another 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.
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 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 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-arrythmic drug. It is used to restore normal heart rhythm and maintain a regular, steady heartbeat. It is also used to prevent certain types of 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 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 bioavailability 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.
Steps to avoid such 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.
This article is intended for informational purpose only. It should not take the place of advice from your doctor, pharmacist, or other health-care professionals. Always ask them if you have unusual symptoms, or any problem when you are using your medicines. This article may not cover all medicines or every type of medicines.
- 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.
- https://www.researchgate.net/publication/5801710_Interaction_between_mercaptopurine_and_milk [accessed Aug 18 2018].
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© 2018 Sherry Haynes