If you take diuretics for health reasons, it's important to avoid other medications, as well as herbal supplements and vitamins, that could lead to an interaction. That includes some teas that act as diuretics.
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Diuretics (aka water pills) are often used to treat high blood pressure, according to the Mayo Clinic. While different medications work in different ways, the general idea is that these pills prompt the kidneys to excrete more sodium in the urine. This, in turn, helps remove water from the bloodstream. With less fluid pumping through the body's system, blood pressure is reduced. These medications are also used to treat congenital heart failure and edema, as well as some kidney and liver diseases, per the Texas Heart Institute.
If you drink diuretic teas while taking water pills, you could essentially double up that diuretic effect — and this could be dangerous as you might be at risk of developing dehydration and low potassium in the body (aka hypokalemia). Hypokalemia can already be a risk with certain types of diuretics on their own, per the Mayo Clinic.
Registered dietitian Sue-Ellen Anderson-Haynes shares some teas you mind find in your health food store or grocery that act as diuretics.
Made from the leaves of the nettle plant, stinging nettle tea is a diuretic that "acts on the lungs, kidneys, bladder and blood," Anderson-Haynes says. Nettle-derived products may come in the form of a tea, powder or capsule and can be used as tincture or juice, she says.
The health concerns surrounding stinging nettle tea are numerous as in some people it can cause "diarrhea or constipation and upset stomach," Anderson-Haynes explains. "It also lowers blood pressure, can increase or decrease blood sugar and may cause uterine contractions."
Stinging nettle can interact with a variety of medications, including diuretics, medications for high blood pressure, nonsteroidal anti-inflammatory drugs (NSAIDs) and medications for diabetes, per Mount Sinai.
Horsetail tea, which may also be a powder, capsule or tincture, affects the kidneys as well as the heart, blood and lungs, Anderson-Haynes says. It can irritate the intestine with medicinal use.
"Horsetail tea can lower potassium levels," she says. Since some blood pressure medications do the same, taking them together isn't recommended. Drinking horsetail tea in conjunction with diuretics can also lead to dehydration, per Mount Sinai.
"And if you're allergic to carrots and nicotine, you may also be sensitive to the affects of horsetail," Anderson-Haynes says. People using nicotine patches and heavy drinkers should not consume horsetail, according to Mount Sinai.
You should speak to your health care provider before drinking horsetail tea (or consuming it in other ways) if you are taking prescription medications, according to Mount Sinai. And, note that even if your doctor clears you to drink horsetail tea, you should not do so for an extended amount of time, per Mount Sinai.
You're probably familiar with this common herb — along with garnishing dishes, it's also used in diuretic teas.
"Parsley can act on the kidneys, the bladder, stomach, liver and gallbladder when consumed as a tea made from the root, leaves and seeds or as a juice, powder or oil," Anderson-Haynes says. Parsley tea is a diuretic that could up your risk of dehydration and interact with some medications. "But it's likely safe when eaten in the amounts you find in food," she adds.
Still, parsley tea can increase blood pressure and lower blood sugar and medicinal amounts aren't considered safe if you have kidney disease, anemia or diabetes (check with your doctor first).
Dandelion tea may sound innocent enough, but this diuretic affects the same organs — the kidneys, bladder, stomach, liver and gallbladder — as the other teas listed above. Just as with the other diuretic teas, drinking it could put you at risk for an electrolyte imbalance, per Mount Sinai.
"Dandelion can be simmered and consumed as tea or taken as a tincture or capsule when the root and leaves are powdered," Anderson-Haynes says. In addition to interacting with prescription diuretics, "dandelion may also cause stomach upset, heartburn, diarrhea, lower blood sugar and slowed blood clotting," she says.
While there is ample history of dandelion being used as a diuretic, there aren't high quality studies done in people (not animals) to back up this use, according to Mount Sinai.
Due to the potential for interactions with diuretics, as well as other medications, consult with your doctor if you take any prescribed medications before drinking dandelion tea, per Mount Sinai.
What About Black and Green Tea?
While these other teas, including white, oolong, green and black, aren't herbal ones, "they all come from the same plant called camellia sinesis," Anderson-Haynes says.
By way of a primer, "black tea is actually green tea that's been oxidized or exposed to air, while white tea is picked before the leaves open and oolong is fermented less than black tea," Anderson-Haynes explains.
All of these teas — black, green, oolong and white — contain caffeine, which is a known diuretic, Anderson-Haynes says. Take caution drinking these teas if you're on a prescription diuretic. "Generally, these are safe to consume, except in large amounts, like four or five cups a day," she says. At that level, side effects can occur, including increased blood pressure, anxiety, fast breathing and sleeplessness.
A word about pu-erh tea, which is a type of fermented tea. This choice has similar side effects and contraindications as the others here as it also contains caffeine. "And it has the added risk of digestive issues due to the fermented effect if you drink large amounts of it," Anderson-Haynes says.
The bottom line: Speak with your doctor before choosing any of these teas (herbal or teas derived from the camellia sinesis plant) if you're taking a diuretic to treat high blood pressure or another condition.
Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.