Risks Associated with Any Medication or Dietary Supplement: What You Need to Know Before Taking Anything

Barbara Lalicki January 16, 2026 Medications 13 Comments

Many people assume that if something is labeled "natural," it’s safe. That’s a dangerous myth. Whether it’s a prescription pill, an over-the-counter painkiller, or a herbal supplement you bought online, anything you put into your body can harm you. The truth is, both medications and dietary supplements carry real, sometimes life-threatening risks - and most people have no idea how serious those risks really are.

Supplements Aren’t Regulated Like Medicines

In the United States, dietary supplements are treated like food, not medicine. That means companies don’t have to prove they’re safe or effective before selling them. The FDA can only step in after someone gets hurt. Between 2015 and 2022, over 23,000 people ended up in emergency rooms because of supplement-related problems. That’s not a small number - it’s nearly 65 people every day.

Take St. John’s wort, for example. It’s sold as a natural remedy for mild depression. But it doesn’t just sit quietly in your body. It actively interferes with how your liver processes other drugs. Studies show it can slash the effectiveness of birth control pills by 13-15%. For someone relying on those pills to prevent pregnancy, that’s a huge risk. It also drops levels of cyclosporine - a drug used after organ transplants - by up to 60%. That could mean organ rejection.

Even something as simple as vitamin E can be dangerous. At doses above 400 IU per day, it increases the risk of hemorrhagic stroke by about 10%. And that’s not even counting the people who take it with blood thinners like warfarin. The combination can turn a minor cut into a medical emergency.

Herbs Are Powerful - and Dangerous

Herbal supplements are among the most problematic. They’re complex mixtures of chemicals, and we don’t always know what’s inside them. A 2022 FDA report found that 38% of supplement-related adverse events came from herbal products - even though they make up only 19% of the market. Why? Because they’re potent.

Ginkgo biloba is a popular supplement for memory and circulation. But it also thins the blood. When taken with aspirin or warfarin, it can increase bleeding time by 20-30%. One case reported to the FDA involved a 68-year-old woman who started taking ginkgo alongside her daily aspirin. Two weeks later, she had a massive gastrointestinal bleed and needed a blood transfusion.

Goldenseal is another culprit. It can interfere with how your body absorbs antibiotics and other medications. Garlic supplements? They can do the same. And bitter orange - often found in weight-loss products - can spike your blood pressure by 10-15 mmHg and trigger irregular heartbeats. In 2023, the FDA added bitter orange to its list of high-risk ingredients after dozens of heart-related emergencies were linked to it.

Drug Interactions Are Silent Killers

The biggest danger isn’t the supplement itself - it’s what happens when it meets your medication. These interactions don’t always cause immediate symptoms. They creep up slowly. You might feel fine for weeks, then suddenly crash.

Take vitamin K. It’s essential for blood clotting. But if you’re on warfarin (a common blood thinner), extra vitamin K can undo the drug’s effect. Studies show it can reduce warfarin’s effectiveness by 40-50%. That means clots form when they shouldn’t - increasing your risk of stroke or pulmonary embolism.

Then there’s chemotherapy. Antioxidants like vitamins C and E are often taken to "support immunity" during cancer treatment. But research from the American Cancer Society shows they can reduce chemotherapy effectiveness by 25-30% in certain regimens. One radiation oncologist told a patient to stop all supplements because vitamin E caused severe skin burns during treatment - delaying therapy for three weeks.

Even common painkillers like ibuprofen can be risky. Taking them with fish oil or garlic supplements increases bleeding risk. And if you’re on antidepressants like sertraline, mixing them with St. John’s wort can trigger serotonin syndrome - a rare but deadly condition that causes high fever, seizures, and organ failure.

Small patient with supplement list on clipboard while doctor shows warning icons.

What You’re Not Telling Your Doctor

Here’s the scary part: half of all Americans take dietary supplements. But only one-third tell their doctor about it. That means your doctor is flying blind.

You might think, "It’s just a multivitamin," or "I only take it once a week." But your body doesn’t care about your intentions. It reacts to the chemicals. A 2023 Reddit post from a user named u/HealthyJourney89 described taking 500mg of ashwagandha for stress - while also on blood pressure medication. Within days, they had insomnia, heart palpitations, and dizziness. They didn’t realize the two could clash.

Doctors can’t help you if they don’t know what you’re taking. That’s why the NIH created a simple tool called "My Dietary Supplement and Medicine Record." It’s free, printable, and used by over 1,200 clinics. Write down every pill, capsule, powder, or tea you take - even if you think it’s harmless. Bring it to every appointment.

Who’s Most at Risk?

Some people are far more vulnerable than others.

- Older adults: Their livers and kidneys don’t clear drugs as efficiently. High doses of vitamin D - especially over 300,000 IU monthly - increase fall and fracture risk by 15-20%.

- Cancer patients: Supplements can interfere with chemo, radiation, and immunotherapy. The American Cancer Society advises avoiding all supplements during treatment unless approved by your oncologist.

- Pregnant women: Certain herbs like black cohosh and dong quai can trigger contractions. Even high-dose vitamin A can cause birth defects.

- People with liver or kidney disease: Your body can’t process toxins the same way. Green tea extract, for example, has caused liver damage in over 20% of supplement-related liver injury cases.

Tiny figures with supplements facing a giant sign warning against body experiments.

What You Should Do Right Now

You don’t need to stop all supplements. But you do need to be smarter.

Stop assuming "natural" means safe. Just because it’s sold in a health food store doesn’t mean it’s harmless.
Tell your doctor everything. Not just prescriptions. Not just vitamins. Every herb, mineral, protein powder, or energy shot.
Check for red flags. If a supplement claims to "boost immunity," "cure arthritis," or "replace medication," walk away. Real science doesn’t work that way.
Avoid multi-ingredient products. The FDA found that 73% of serious adverse events come from supplements with 5+ ingredients. More ingredients = more unknown interactions.
Buy from trusted brands. Look for third-party testing seals like USP, NSF, or ConsumerLab. Products sold on Amazon or Instagram are far more likely to be contaminated or mislabeled.

What to Do If Something Goes Wrong

If you feel strange after starting a new supplement - dizziness, nausea, rash, rapid heartbeat, or unusual bleeding - stop taking it immediately. Don’t wait. Don’t hope it goes away.

Call your doctor. Go to urgent care. If it’s severe, call emergency services.

And report it. The FDA’s MedWatch system accepts reports from anyone. In 2022, they received over 18,000 supplement-related reports. Every report helps them spot dangerous trends. You could be the one who prevents someone else’s tragedy.

Final Thought: Your Body Isn’t a Lab Experiment

We live in a world that pushes quick fixes. Supplements are marketed as easy solutions to complex problems. But your body is not a machine you can tweak with a pill. Every chemical you introduce has consequences.

The safest approach isn’t to take more - it’s to take less. Ask yourself: "Do I really need this?" If the answer isn’t clear, wait. Talk to your doctor. And remember: if something sounds too good to be true, it probably is.

Are dietary supplements safer than prescription drugs?

No. Prescription drugs go through years of testing before approval. Supplements don’t. The FDA can’t remove a supplement from the market unless it proves the product is unsafe - which often takes years. Meanwhile, thousands of people end up in emergency rooms each year because of supplement side effects or interactions.

Can I take supplements with my blood pressure medication?

Some can be dangerous. Bitter orange, yohimbe, and high-dose ginseng can raise blood pressure. Others, like garlic and fish oil, can make your medication work too well and drop your pressure too low. Always check with your doctor before combining any supplement with blood pressure drugs.

Why do doctors warn against supplements during cancer treatment?

Antioxidants like vitamins C and E can interfere with how chemotherapy kills cancer cells. Some herbs alter liver enzymes that break down drugs, making treatment less effective or more toxic. Even skin reactions from supplements can delay radiation therapy. Most oncologists recommend stopping all supplements unless specifically approved.

Is it safe to buy supplements online?

It’s risky. Nearly half of all supplement-related adverse events come from products bought online, where quality control is weak. Many contain hidden drugs, heavy metals, or incorrect dosages. Stick to brands with third-party testing (USP, NSF, ConsumerLab) and avoid products sold on social media or marketplaces like Amazon without verified reviews.

What should I do if I experience side effects from a supplement?

Stop taking it immediately. Contact your doctor or go to urgent care if symptoms are severe - like chest pain, trouble breathing, bleeding, or confusion. Then report the incident to the FDA through MedWatch Online. Your report helps protect others.

Do multivitamins have risks?

Yes. While they seem harmless, high doses of fat-soluble vitamins like A, D, E, and K can build up and cause toxicity. Vitamin A overdose can damage your liver and cause vision problems. Too much vitamin D leads to dangerous calcium buildup in your blood. Most people get enough vitamins from food - extra doses often do more harm than good.