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Surprising Side Effects of 5 Popular Supplements

Loads of people take supplements to help them sleep, prevent a cold, boost energy, and even improve memory. But supplements aren't regulated by the FDA, so the manufacturers of these pills don't have to list any potential side effects. While studies on supplements and their side effects are limited and often inconclusive, we asked Sophia DeMonte, rPH, a COSTCO pharmacist, and APhA spokesperson and Dr. Carolyn Dean, MD, ND author of The Magnesium Miracle to detail some of the unexpected symptoms five common supplements may cause:

Valerian Root

What it's used for: Sleeplessness and insomnia.

Possible side effects: Vivid dreams.

Valerian has been used for centuries as a calming aid, muscle relaxant, and to foster deep sleep. According to Dr. Dean, vivid dreams may occur as a result.

"If you sleep poorly and wake often you may not be getting into a deep enough sleep to dream, so if you take Valerian and notice you dream more, what's likely happening is you're getting into a deeper sleep," she says.

So if you take valerian and experience a memorable nocturnal adventure, it's not the Valerian that's lighting up your night, but the deeper sleep it's helping you get.

Fish Oil

What it's used for: To promote heart health and reduce cancer risk.

Possible side effects: Heartburn, burping, and diarrhea.

Fish oil caplets are a great way to boost intake of omega-3s, but the oil can cause gastric issues, more noticeable heartburn, and belching that's combined, unpleasantly, with a fishy aftertaste. Fortunately it's pretty easy to control these symptoms. Swallow the capsule in the middle of a meal so it mixes with the food, which improves digestion, and look for high-quality "purified" supplements, which cause less fishy burps.

Ginkgo Biloba

What it's used for: To enhance memory.

Possible side effects: Headache, nausea, and other gastrological disorders, as well as bleeding risk.

This supplement gained popularity a few years back as a way to boost memory, but not only are there few studies that support this, there is evidence that it could thin blood, making it dangerous for anyone on blood thinning medications (or anyone getting surgery—even a dental procedure). Plus, raw ginkgo seeds contain large amounts of a potentially deadly toxin. If you're a fan of the seeds, limit your intake to no more than a few cooked ginkgo seeds per day to reduce risk of poisoning.

Ginseng

What it's used for: To boost energy.

Possible side effects: Heart palpitations and increased blood pressure.

Ginseng is made from the root of a flowering plant, and, like Ginkgo Biloba, experienced a surge in popularity a few years back as a natural energy booster. It works, more or less, but there are questions about its safety.

"Ginseng affects hormone receptors in the brain by stimulating the secretion of the adrenal hormone, and this results in an energy boost," Demonte says.

This can also result in a racing heart and a spike in blood pressure, so if you're on blood pressure meds or have a family history of hypertension, steer clear.

Echinacea

What it's used for: To boost immunity.

Possible side effects: Allergies.

According to Demonte, most evidence of echinacea's cold-thwarting benefits are anecdotal, and ironically, if you have allergies to ragweed, daisy, aster, or chrysanthemum, you can be allergic to the product itself, possibly creating similar symptoms to a cold.