One pill from the pharmacy, a cold-and-flu remedy from the supermarket or a supplement a friend swore by – add a glass of wine to any of these and suddenly an ordinary evening can turn deadly.
Every year, millions of Americans unknowingly combine medications that can dangerously suppress breathing, trigger internal bleeding, overwhelm the liver or send blood pressure crashing to fatal levels.
Adverse drug events – including dangerous medication interactions, overdoses and prescription mistakes – send more than 1.5 million Americans to emergency rooms every year, according to the CDC.
Experts believe the true toll is likely even higher, because many medication-related complications are never formally identified as drug interactions.
While doctors do not intentionally prescribe dangerous combinations, things get messy when multiple physicians are involved with one patient.
In the fragmented reality of modern healthcare, one patient may see a psychiatrist for anxiety, an orthopedist for back pain and a primary care physician for blood pressure. They each may prescribe something as a fix for the respective ailment, with no one fully tracking every prescription, supplement and over-the-counter remedy already in the patient’s pillbox.
That means potentially deadly combinations can slip through the cracks with alarming ease. So which medications worry pharmacists most?
Here, Jobby John, a pharmacist of 15 years and CEO of Nimbus Healthcare, reveals the drug combinations he believes every American should know about.
Mixing certain over-the-counter drugs, herbal supplements, prescription medications and more could be deadly
Opioids and benzodiazepines
‘This is the one I lose the most sleep over,’ John said.
Combining a prescription painkiller – including hydrocodone, oxycodone or tramadol – with an anti-anxiety drug like Xanax, Valium, Ativan or Klonopin carries an FDA black box warning, the agency’s strongest possible safety alert.
Both drug classes cause respiratory depression, meaning they slow breathing.
Opioids work by binding to brain receptors that control pain, but a dangerous side effect is that they also slow the brain’s signal to breathe. Benzodiazepines calm anxiety by boosting a brain chemical called GABA, which also suppresses the central nervous system, including breathing.
When taken together, the effects are multiplied. This dramatically increases the risk of overdose and death.
A dose of each medication that may be safe on its own can become lethal in combination, John said.
Patients taking both as prescribed may mistakenly assume they are protected from harm because they are following medical advice.
But John warned this is not necessarily true.
‘The patient does not have to be misusing anything,’ he said. ‘If you legitimately need both prescriptions, every prescriber needs to know about every bottle in your cabinet. Alcohol stays out of the equation entirely.’
Cold and flu medicines
Acetaminophen is the most common drug ingredient in America, according to the American Liver Foundation.
It is found not only in Tylenol, but in hundreds of over-the-counter cold, flu, sinus and sleep medications, as well as prescription painkillers including Percocet, Vicodin and Norco.
Many people have no idea they are taking multiple products containing the same drug.
‘Patients walk in with a head cold, take NyQuil at bedtime, swallow Tylenol for body aches, and grab Excedrin for the headache,’ John said. ‘Three bottles, one active ingredient.’
The safe daily ceiling is 4g of acetaminophen a for healthy adults – roughly eight extra-strength Tylenol tablets in 24 hours – and even less for people who drink alcohol regularly or have liver problems.
Some cold-and-flu remedies contain as much acetaminophen in a single dose as two extra-strength Tylenol tablets, meaning accidental overdoses can happen far more easily than many people realize.
Exceeding that limit, even slightly, can overwhelm the liver’s ability to process the drug. When this happens, a toxic byproduct begins building up and killing liver cells.
The danger is compounded by how deceptively mild the early symptoms can appear.
Nausea, vomiting and fatigue often develop within the first 24 hours. Many people mistake them for a stomach bug or the illness they were already treating.
By the time more severe symptoms such as jaundice, confusion or bleeding emerge, significant liver damage may already have occurred.
Acetaminophen poisoning is responsible for roughly 56,000 emergency room visits, 2,600 hospitalizations and about 500 deaths every year in the United States.
Nearly all of these cases are preventable.
Experts say patients should carefully read medication labels, avoid taking multiple acetaminophen-containing products simultaneously and never exceed the recommended daily limit – even if symptoms persist.
Blood thinners
Warfarin remains one of the nation’s most widely prescribed blood thinners and is commonly used to prevent strokes and dangerous blood clots.
Aspirin, taken daily by millions of Americans as a painkiller and heart medication, is also a blood thinner.
Taken alongside warfarin or other prescription blood thinners, it can sharply increase the risk of dangerous internal bleeding – including in the stomach or brain.
‘Warfarin is still commonly prescribed, particularly among older patients with atrial fibrillation, artificial heart valves or a history of blood clots,’ John said.
He explained that the drug has a very narrow safety margin, meaning even small changes in dosage or interactions with other medications can significantly raise the risk of dangerous bleeding.
The problem is that aspirin is hidden in more products than many people realize.
It is found not only in standard tablets, but also in some headache remedies, cold medications and even certain antacids.
A patient treating what seems like a harmless headache could unknowingly double up on blood-thinning medications, potentially leading to bleeding in the stomach, brain or other organs.
‘When patients on warfarin reach for ibuprofen, naproxen or aspirin, they are stacking two anti-clotting drugs that work on different pathways,’ John explained.
Antidepressants, ADHD pills and cold medicines
Millions of Americans take antidepressants such as Zoloft, Prozac and Lexapro every day.
On their own, the medications are generally considered safe and effective when taken correctly.
But pharmacists warn problems can arise when patients combine them with other common medicines and supplements that affect the same chemicals in the brain.
‘A lot of people do not realize cough medicines, certain painkillers, herbal supplements and ADHD medications can interact with antidepressants,’ John said.
Products including the painkiller tramadol, cough syrups containing DXM, the herbal remedy St John’s wort and some ADHD medications can all increase levels of serotonin – a brain chemical linked to mood and emotions.
Taking several serotonin-boosting substances together can cause levels to build dangerously high, triggering a reaction known as serotonin syndrome.
Symptoms can include sweating, agitation, diarrhea, tremors, rapid heartbeat and confusion. In severe cases, it can lead to seizures, dangerously high fever and organ failure.
‘People often assume herbal supplements are automatically harmless because they are “natural,”‘ John said. ‘But St John’s wort can interact with antidepressants in very powerful ways.’
Viagra and nitrate heart drugs
Nitrate medications are commonly prescribed to treat chest pain and heart disease.
These drugs – including nitroglycerin, isosorbide mononitrate and isosorbide dinitrate – work by relaxing and widening blood vessels to improve blood flow to the heart.
But pharmacists warn they should never be combined with erectile dysfunction drugs such as Viagra or Cialis.
ED medications also widen blood vessels to increase blood flow. When the two drugs are taken together, blood pressure can suddenly crash to dangerously low levels.
That can leave the brain and heart starved of oxygen, potentially triggering fainting, collapse, heart attack, stroke or even sudden cardiac arrest.
Symptoms often begin with headache, flushing and dizziness before rapidly becoming life-threatening.
‘Take both and you can drop your blood pressure low enough to die,’ John said.
He warned the danger is especially serious because the men most likely to need ED drugs are often the same patients already taking heart medications.
‘If you are on nitrate medications for your heart, ED drugs are generally off the table,’ he said. ‘There are alternatives, but patients need to discuss them with their doctor rather than mixing medications on their own.’
Experts say the safest way to avoid dangerous drug interactions is to keep an up-to-date list of every prescription medication, supplement and over-the-counter remedy you take – and make sure every doctor and pharmacist involved in your care sees it.
