Doctor holding prescription bottle, talking to patient

5 Harmful Medication Interactions You Need to Know

You have a headache, so reach for the painkillers - but have you read the label? Several medications and supplements on the market can interact with each other and have harmful side effects. Learn about some common interactions with medications and remember to always talk to your doctor before you introduce a new supplement or medication into your system.

1. Medications With the Same Active Ingredient

If you start taking a new medication that has the same active ingredient as another medication you are taking, there is a risk of an overdose of that particular ingredient. If you experience symptoms of an overdose such as seizures, vomiting, or confusion, call 911 or seek emergency medical attention.

2. Pain medication

Painkillers such as aspirin, non-steroidal anti-inflammatory drugs NSAIDs and acetaminophen can cause severe bleeding when taken in conjunction with warfarin (an anticoagulant). This is due to their enhancing effect on anti-clotting compounds.

3. Melatonin

Some medications, such as birth control, can increase the amount of melatonin your body produces, so taking melatonin in combination with these medications can lead to an overdose. Some signs of melatonin overdose include dizziness, nausea and diarrhea. In case of melatonin overdose, call the Poison Control Center.

Although birth control pills can affect the safety of melatonin, there is no evidence that melatonin affects birth control negatively by making it less effective or increasing the likelihood of side effects due to birth control. There are also no known interactions between melatonin and ibuprofen.

However, melatonin may reduce the effectiveness of certain other medications, including SSRIs (selective serotonin reuptake inhibitors) and blood pressure medications. If you have trouble falling or staying asleep, talk to your doctor about safe options that supplement your current medication or visit a sleep center.

4. Rifampin

Rifampin is an antibiotic used to treat tuberculosis and Neisseria meningitidis, a type of bacteria that can cause meningitis. Using rifampin with other medications may reduce the effectiveness of these medications. Some medications that rifampin weakens are carbamazepine (used to control seizures and phenobarbital (an anticonvulsant).

5. St. John's Wort

St. John's Wort is a supplement that some doctors prescribe to treat depression. However, St. John's Wort can reduce the effectiveness of several medications, including antidepressants, some cancer medications, and warfarin.

Always talk to your doctor before taking a new medication or supplement and read the medication label to make sure you are taking it safely.

If someone has sudden overdose symptoms such as dizziness, vomiting, or unconsciousness, call 911 or call the nearest St. Luke's Health emergency room.

ScienceDirect | Drug-drug Interactions
FDA | Drug Interactions
NIH | St. John's Wort and Depression: In Depth
AAFP | Clinically Significant Drug Interactions
Healthline | Blood Thinners: Uses, Side Effects, and Drug Interactions
Healthline | Melatonin and Birth Control: Is It Safe?
Healthline | Melatonin Overdose: How Much Melatonin Should I Take?
E Medicine Health |  Drug Overdose Symptoms & Treatment
MedlinePlus | Rifampin
My Virtual Medical Centre | Blood Clotting: International Normalised Ratio (INR)
Medline Plus | Carbamazepine
Rx List | Phenobarbital

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