When a health professional prescribes a medication, they provide instructions on taking it. When someone picks up a new prescription at the pharmacy, the most common questions are often regarding the instructions on medication dosing frequency, and if the new medicine could cause bothersome side effects such as nausea and upset stomach. Along with information regarding proper storage, knowing whether certain medications should be taken on an empty stomach or with food is as crucial as taking the drug exactly as prescribed, meaning the right amount and the correct frequency. The reason is that the oral administration of certain medications with food can lead to a food-drug interaction. Please continue reading to learn why some medications should be taken with food. We will also list some examples of such medicines.

What are food-drug interactions?

Food can affect how certain medications work in the body. This is referred to as food-drug interaction. Sometimes food can prevent certain medicine from working properly. There are also instances when food can intensify the medication’s effects, in turn worsening the side effects.

The FDA defines herbal supplements as food, and not drugs; therefore, they can remove certain herbal supplements from the market if they are found to be unsafe; otherwise, it is up to the manufacturers to make sure that they are safe before they make them available to be sold to consumers. While certain foods can interact with prescriptions and over-the-counter drugs, herbal supplements can also cause undesirable effects on the body as a result of herb-drug interactions. You should talk to your doctor or pharmacist before taking herbal supplements to avoid harmful adverse effects.

The interaction between vitamin K and the blood thinner warfarin is one example where food causes the medication to be less effective. For example, green leafy vegetables such as spinach, kale, broccoli, and Brussels sprouts contain high levels of vitamin K. It doesn’t mean you can’t eat any of these vegetables while on warfarin therapy. The key is to consume about the same amount of vitamin K every day. On the other hand, alcohol intake greater than three drinks daily can cause warfarin to be more potent, increasing the risks of bleeding.

As mentioned, food can make side effects worse. For instance, monoamine oxidase inhibitors (MAO inhibitors) are an older generation of antidepressants. Examples of MAO inhibitors include isocarboxazid (Marplan), phenelzine (Nardil), and selegiline (Emsam). Combining an MAO inhibitor with foods high in tyramine can cause the tyramine levels to be dangerously high; this can lead to a spike in blood pressure that requires immediate medical treatment to avoid organ damage. Some examples of food with high tyramine content are aged cheese, cured meat, hot dogs, bacon, and other processed food, as well as soybean products, and alcoholic beverages. If you take an MAO inhibitor, it is best to keep a list of foods and beverages that are high in tyramine to avoid this dangerous interaction.

The effect when combining alcohol with CNS (central nervous system) depressants is another classic example of food and beverages causing the worsening of side effects. For example, taking sleeping pills like zolpidem (Ambien), eszopiclone (Lunesta), and zaleplon (Sonata) with alcohol can lead to serious side effects like extreme drowsiness and slowed breathing. This interaction can also occur when combining alcohol with anxiety drugs such as diazepam (Valium), alprazolam (Xanax), and lorazepam (Ativan). Additionally, gut secretions can raise or reduce the absorption of certain medicines.

Calcium-rich foods or supplements have been shown to reduce the bioavailability of certain antibiotics, meaning calcium affects the absorption of these drugs in the bloodstream, making them less effective. Examples of this include certain tetracyclines antibiotics and fluoroquinolones, such as Levaquin (levofloxacin), Avelox (moxifloxacin), and Cipro (ciprofloxacin). The rule of thumb is to avoid calcium-containing products such as yogurt, milk, or ice cream at least 2 hours before or 6 hours after taking the antibiotics.

Also, watch out for calcium-rich foods if you take medication for hypothyroidism, such as Synthroid (levothyroxine), as calcium can reduce the effectiveness of this medication. Synthroid (levothyroxine) should be taken first thing in the morning to increase its absorption. You should wait at least 4 hours after taking this thyroid medication to consume dairy products, antacids, and calcium supplements.

Grapefruit juice is one of the most widely studied examples of food-drug interactions. Potential interaction between grapefruit juice with drugs like certain statins (simvastatin), calcium channel blockers, and anticoagulants (warfarin), can significantly increase the levels of these drugs in the bloodstream and increase the risk of side effects.

On the other hand, certain medicines should be taken with food for the reasons described below. Essentially, you should follow your doctor’s instructions to obtain maximum benefit from a medication.

Do all medications need to be taken with food?

No, all medications do not need to be taken with food. In fact, some medications need to be taken on an empty stomach because the presence of food or the acidic environment in the stomach after a meal results in decreased absorption of the drug.

Even medications in the same class of drugs may need to be taken differently, some with and some without food, because of physiological changes. For example, the statin medication lovastatin (used to treat high cholesterol) is absorbed better when taken with food. However, co-administration with food significantly reduces the absorption of another statin medication, rosuvastatin. Other statins like pravastatin, simvastatin, and fluvastatin can be taken with or without food.

Keep in mind that even if there is no food-drug interaction, your doctor may instruct you to take certain medicine around mealtimes because it makes it easier for you to remember to take your pills.

How much food is needed when medicine says to take with food?

Unless the instructions specify the amount of food, a snack or light meal is often acceptable when instructed to take a medication with food. To reduce the risk of side effects like stomach irritation or stomach inflammation, you can take the medicine with a small amount of food such as a glass of milk, a few crackers, a sandwich, a granola bar, or some yogurt, and this is usually enough. To reduce nausea, take the medicine with a snack and wait 15-30 minutes to see how you feel before taking your medicine, especially with expensive medication or those that are hard to replace, such as controlled substances, to avoid wasting a dose.

Which medications should be taken with food

Non-steroidal anti-inflammatory drugs (NSAIDs)

NSAIDs like ibuprofen (Motrin, Advil) and naproxen (Aleve) are best taken with food or dairy products to minimize the risk of stomach irritation and ulcers.

Antacids

You should take antacids for acid reflux with food or soon after eating because this is when your symptoms of heartburn are most likely to occur.

Certain antifungals

Medications for oral thrush or mouth ulcers, such as miconazole gel or liquid nystatin, should be used after meals. Taking them before meals can make the medicine ineffective because eating food washes the medicine away. On the other hand, the oral suspension of the antifungal medication posaconazole should be taken with a high-fat meal because this will increase the absorption of the drug from the stomach and small intestine into the systemic circulation. Interestingly, posaconazole oral tablets can be taken with or without food which is an advantage, especially for those who have problems ensuring adequate food intake.

Certain antibiotics

You should take certain antibiotics such as cefpodoxime, amoxicillin/clavulanate (Augmentin), rifabutin (Mycobutin), and nitrofurantoin (Macrodantin, Macrobid) with food to reduce side effects like stomach pain and nausea and for better intestinal absorption of the antibiotics.

Anti-diabetic medications

Sulfonylureas (glipizide, gliclazide, glibenclamide, and glimepiride) are used to reduce blood sugar levels in people with diabetes. These medicines should be taken around 30 minutes before a meal to avoid the risk of significant hypoglycemia (low blood sugar). Other medications used to treat type 2 diabetes, such as acarbose, should be taken with the first bite of a main meal to maximize their effectiveness. Metformin should be taken with meals to reduce stomach and bowel side effects.

Anti-gout medications

Medicines like allopurinol that are used to treat gout should be taken with or after meals to avoid an upset stomach. Also, you should drink plenty of fluids while on this medicine to reduce your risk of kidney stones.

Steroid medicines

It is best to take steroid medicines like dexamethasone and prednisolone with meals to stop them from irritating your stomach.

Enzyme supplements

People with chronic pancreatitis may be prescribed enzyme supplements like Creon, Pancreaze, and others. These medicines should be taken with meals because they work to help the body process the meal.

Bromocriptine

This medication is used to treat certain menstrual problems, infertility, and abnormal milk production. It should be taken with food to help lessen nausea.

HIV medications

Certain medicines used to treat HIV, such as ritonavir, should be taken with meals because food allows the body to absorb the medicine better.

References:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3191675/
https://www.nhs.uk/common-health-questions/medicines/why-must-some-medicines-be-taken-with-or-after-food/
https://www.nhs.uk/common-health-questions/medicines/does-grapefruit-affect-my-medicine/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4548036/#
https://journals.asm.org/doi/10.1128/AAC.05000-14
https://www.mayoclinic.org/drugs-supplements/allopurinol-oral-route/precautions/drg-20075476
https://www.mayoclinic.org/drugs-supplements/bromocriptine-oral-route/precautions/drg-20062385
https://www.mayoclinic.org/drugs-supplements/ritonavir-oral-route/proper-use/drg-20067063
https://familydoctor.org/herbal-health-products-and-supplements/

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