Understanding Medication Interactions: What You Need to Know

Mar 29, 2024 | Stories

As patients, we are always instructed to check with our provider before beginning a new medication or dietary supplement to avoid drug interactions – but what exactly does this mean?

A drug interaction occurs when a drug, a supplement, food, or other factor affects the way that a body processes medication.[1] These interactions can affect the body’s digestion or absorption of medication. As a result, drug interactions often have the unintended result of delaying, decreasing, or enhancing absorption of a drug.[2]

Drug interactions can be dangerous because they can lead to a medication staying in the body for too long, building up to potentially toxic levels, and potentially turning a standard dose into an overdose. Alternatively, if a medication breaks down too quickly, it will not be in the body for long enough, causing the drug to not be less potent or not effective.

Drug-Drug Interactions

When we think of medication interactions, drug-drug interactions are often the first to come to mind. These interactions occur when two or more drugs are taken at the same time, where one drug affects the cytochrome enzyme that processes the other.

Levothyroxine and Calcium. Levothyroxine is a commonly prescribed medication for patients with lower thyroid levels. Calcium, a common ingredient in dairy and vitamin supplements, readily available over the counter, can combine with Levothyroxine in the gastrointestinal tract and prevent the Levothyroxine from being absorbed into the body. It is recommended to take Levothyroxine on an empty stomach 30-60 minutes before morning meal.

Bactrim and Warfarin. Another example of a drug interaction to look out for is that between antibiotic, Bactrim, and blood thinner treatment, Warfarin. When taken together, patients face an elevated risk of bleeding, especially among the elderly and those with liver or kidney impairment.

Drug-Food Interactions

When a food or beverage affects how a medication works, it is a drug-food interaction, which can also be referred to as a nutrient reaction. One of the most well-known drug-food interactions is alcohol, which interacts with several common classes of drugs, including antibiotics, antidepressants, antihistamines, blood thinners, and others.[3]

Minocycline and dairy. While some food-drug interactions are well-known, others are more surprising. The calcium found in dairy products can lower the amount of the antibiotic Minocycline that is absorbed by the body, so doctors recommend taking minocycline at least 1 hour before or 2 hours after eating dairy products like ice cream or cheese.

MAOIs and aged meats. Monoamine oxidase inhibitors, or MAOIs, a class of drugs used to treat depression, stops the body from breaking down a protein called tyramine. Ingesting tyramine-heavy foods, like aged, cured, or smoked meats, while taking an MAOI can lead to tyramine build up, which can cause a sudden rise in blood pressure or hypertensive crisis.

Drug-Conditions Interactions  

Sometimes a patient’s medical condition can affect how certain medications work or have a negative impact on a person’s condition. This is a drug-condition interaction and can be a significant risk to patients who have comorbidities.[4]  

Diphenhydramine and glaucoma. For people with certain types of glaucoma, including narrow-angle glaucoma, antihistamines can dilate the pupil and block drainage from the eye, causing fluid and pressure to build up.[5] This can lead to significant issues for patients, including pain and distorted vision.

Pseudoephedrine and high blood pressure. A common pseudoephedrine side effect is an increase in blood pressure and while this may not be of concern to the average person, for people who already have high blood pressure, it can pose a larger health risk.[6] In addition to the blood pressure risk, Pseudoephedrine can also cause drug-drug interactions with blood pressure medications, causing them to be less effective.[7]

Preventing Drug Interactions

When it comes to understanding medication interactions, it is important to remember that any drug interaction can be serious, which is why it is critical to communicate with your provider and pharmacist about all drugs your taking, including over-the-counter medications, vitamins, and supplements. Adhering to a medication regimen exactly as prescribed and always asking your doctor and pharmacist about potential interactions is the best way to prevent unintended consequences.

Learn more about how MedMinder’s pharmacy can help you easily and effectively manage your medication.

[1] https://www.health.harvard.edu/staying-healthy/7-things-you-can-do-to-avoid-drug-interactions

[2] https://www.goodrx.com/healthcare-access/medication-education/drug-interactions

[3] https://www.pharmacytimes.com/view/there-are-food-drug-interactions-older-adults-should-be-aware-of-as-they-age

[4] https://hivinfo.nih.gov/understanding-hiv/fact-sheets/what-drug-interaction

[5] https://www.coastalvisionva.com/2011/03/27/medications-side-effects-review-antihistamines-and-glaucoma/

[6] https://www.pharmacytimes.com/view/decongestants-and-hypertension-making-wise-choices-when-selecting-otc-medications

[7] https://www.cdc.gov/bloodpressure/medicines.htm

Related Post

MedMinder Pharmacy Now Providing Local Vaccination Services 

MedMinder Pharmacy is excited to announce that they are now offering vaccine clinic services,...
Medication Management: A Powerful Care Manager Tool

Medication Management: A Powerful Care Manager Tool

MedMinder’s partner serves a senior population including high-cost, high needs patients that live with multiple chronic illnesses requiring intense levels of care and multiple medications. The partner leverages care teams in the home and deploys various strategies to...

Signs You May Need to Take on the Role of Caregiver

Signs You May Need to Take on the Role of Caregiver

When it comes to caregiving, there’s no blanket moment in time that applies to everyone or a finite and specific set of criteria that dictates when it’s time to provide care for a loved one. Every person, family, and situation is different, so it’s important to look...

We're Here Whenever You Need Us



Open Hours

Mon - Fri 8AM - 7PM ET
Sat 8AM - 5PM ET
Sun 9AM - 5PM ET


320 Norwood Park South, Norwood, MA 02062