Everything You Need to Know About Drug Interactions
And why “medicine” doesn’t always mean “safe”
When we take a medication, we expect it to help — and most of the time, it does.
But it’s also true that every medication has side effects, and in some cases, these effects are only discovered years after the drug has been approved and widely used.
Unfortunately, drug interactions — when two or more medications affect each other’s action — are also part of that reality.
Where the Risk Lies
Even well-established medications can reveal new adverse effects over time.
Drug interactions happen when one drug alters the effect of another — by increasing, decreasing, or creating unexpected effects.
People who take multiple medications (such as those with chronic diseases, the elderly, or people with multiple conditions) are at higher risk.
When Drugs Interact
Take atenolol, a type of beta-blocker. It can interact with:
Calcium channel blockers (like verapamil or diltiazem) → may cause low blood pressure or a dangerously slow heart rate.
Other drugs that reduce adrenaline → may lead to fatigue, dizziness, or fainting.
This kind of combination always requires careful medical supervision.
Why Some Side Effects Appear Years Later
After years of real-world use, rare side effects and unexpected interactions can emerge.
Our bodies change over time — age, kidney and liver function, new medications — and these changes affect how drugs behave.
Medical knowledge evolves: what was considered “standard care” twenty years ago might not be the best option today.
What We Can Do as Patients (or Caregivers)
Always tell your doctor about every medication and supplement you take.
Ask: “Does this drug interact with the others I’m taking?”
Watch for new symptoms: dizziness, weakness, swelling, fatigue, or heart rate changes.
Never stop a medication abruptly without medical guidance.
Regularly review your medication list with your doctor — some drugs may no longer be necessary.
If you have chronic kidney disease, pay extra attention — many drugs are cleared through the kidneys, and even small changes in function can affect dosage and safety.
Pro tip: you can now check for possible interactions directly on MetaSano IQ.
Just go to the Profile tab, enter the medications you take, and click “Drug Interactions.”
The system will show evidence-based alerts and insights, helping you talk to your doctor in a safer, more informed way.
My example consulting MetaSano IQ
I set my profile to Stage 3A, take Valsartan daily, and occasionally use Tylenol. Here’s the analysis MetaSano IQ generated for me.
1.Medication Interaction Analysis
There are no significant direct drug-drug interactions expected between valsartan (an angiotensin II receptor blocker) and Tylenol (acetaminophen). Unlike non-steroidal anti-inflammatory drugs (NSAIDs), acetaminophen does not typically interfere with the blood pressure-lowering effects of valsartan or significantly impact kidney function when used at recommended doses.
2. Timing & Administration Advice
Valsartan: This medication is typically taken once daily, usually at the same time each day. It can be taken with or without food.
Tylenol (Acetaminophen): This can be taken as needed for pain or fever, with or without food. Follow the dosing instructions on the package or from your healthcare provider, and do not exceed the maximum daily dose.
There are no specific timing requirements to separate the administration of valsartan and Tylenol; they can be taken at the same time if needed.
3. Comorbidity-Related Risks
Given your comorbidity of hypertension:
Valsartan: This medication is prescribed specifically to manage your hypertension. It works by relaxing blood vessels, which helps to lower blood pressure and reduce the workload on your heart. It is a cornerstone of hypertension management.
Tylenol (Acetaminophen): Acetaminophen is generally considered a safe option for pain and fever relief in patients with hypertension. Unlike NSAIDs (e.g., ibuprofen, naproxen), acetaminophen typically does not cause an increase in blood pressure or interact negatively with antihypertensive medications like valsartan, provided it is used within recommended dosages. Patients with hypertension should avoid frequent or high-dose use of NSAIDs unless specifically advised by their doctor, as NSAIDs can raise blood pressure and potentially interfere with blood pressure medications.
Final Thoughts
Medications are powerful tools — but they must be used wisely.
The case of beta-blockers after a heart attack shows that even long-standing treatments need to be reevaluated over time.
So remember:
No medication is completely “harmless.”
Interactions are real — and can be dangerous.
Information is the best medicine.
And now, with MetaSano IQ, you have a smart and practical way to protect yourself and understand your health better.
With care,
Ewerton Lopes - Living with CKD since 2016
CEO of MetaSano and MetaSano IQ
Integrative Nutrition Specialist
Kidney Health Coach
Member of the Quebec Nephrology Society
Gerontologist
Author of the book My Dog, My Healer: My path to overcoming chronic kidney disease