Ginger Tea

Safety, side effects & who should avoid it

For most healthy adults, ginger tea is a low-risk drink. Ginger is generally recognized as safe (GRAS) for use as a food and spice, and NIH's LiverTox database found no reports of liver injury across more than 100 clinical trials, rating ginger an unlikely cause of liver damage. LiverTox does note one case, in Japan, of a woman who developed liver injury while taking a commercial botanical product said to contain ginger; the product was never analyzed, so what caused it is unknown. Two things are worth watching: heartburn, and a possible interaction with blood thinners. Keep in mind that GRAS status covers ginger as a food, not concentrated supplements, and that ginger supplements are not checked by the FDA for potency or purity before they are sold.

Who should avoid it

• Anyone taking warfarin, phenprocoumon, or another anticoagulant should avoid concentrated ginger supplements and clear daily ginger tea with their prescriber.
• People with a bleeding disorder, or on antiplatelet drugs such as aspirin or clopidogrel, until a clinician signs off.
• Anyone with surgery or dental work coming up. Many surgical teams ask patients to stop herbal supplements, ginger included, beforehand. Ask yours.
• People with gallstones or bile duct obstruction should ask a doctor first. Ginger is traditionally used to stimulate bile flow; this caution is precautionary rather than well studied.
• Anyone whose reflux or gastritis reliably flares with spicy food, and anyone who has reacted allergically to ginger.
• Anyone with severe, persistent, or newly unexplained nausea and vomiting should get it looked at rather than self-treat. In pregnancy, being unable to keep fluids down, losing weight, or vomiting many times a day can mean hyperemesis gravidarum, which needs medical care. Vomiting with severe abdominal or chest pain, blood in the vomit, a recent head injury, or signs of dehydration is an urgent problem, not a tea problem.

Possible side effects

• Heartburn and acid reflux, the most commonly reported effect
• Abdominal discomfort, bloating, and gas
• Diarrhea, and occasionally constipation
• Mouth and throat irritation, especially from strong or powdered brews
• In one open-label study of ginger extract capsules, about 13 percent of participants reported treatment-related adverse events, mostly gastrointestinal

Medication interactions

• Warfarin and other vitamin K antagonists: evidence conflicts. An open-label randomized crossover trial in 12 healthy men found recommended ginger doses left INR, platelet aggregation, warfarin clearance, and CYP2C9 activity unchanged. But a case report describes a 76-year-old woman on phenprocoumon whose INR climbed to 10, with nosebleeds, after she began ginger products; it normalized once she stopped. Tea-sized amounts are unlikely to matter, supplements might, and your prescriber should know either way.
• Antiplatelet drugs (aspirin, clopidogrel) and direct oral anticoagulants: no good human trials exist. Ginger constituents inhibit platelet aggregation in laboratory studies, so an additive bleeding risk is plausible but unproven.
• Nifedipine: a review of ginger drug interactions cites a human report that ginger plus nifedipine inhibited platelet aggregation more than either alone, which points toward more bleeding, not less. The finding has not been replicated. If you take a calcium channel blocker, mention regular ginger supplement use to your pharmacist.
• Diabetes medications: a meta-analysis of five randomized trials in type 2 diabetes found no significant pooled effect of ginger on fasting glucose or HbA1c, though two individual trials showed reductions. A dangerous drop in blood sugar therefore looks unlikely. Still, if you take insulin or a sulfonylurea, where low blood sugar is a real risk, tell your prescriber before you start taking ginger supplements daily, and keep monitoring as usual.
• Drugs cleared by CYP2C9 and CYP3A4: a molecular docking and modeling study predicted ginger components could inhibit these enzymes. That is a computer prediction, not a documented clinical interaction, but worth mentioning to a pharmacist.

Pregnancy & breastfeeding

Early-pregnancy nausea is ginger's best-supported use, and NCCIH states that ginger use during pregnancy may be safe. In a Norwegian cohort of 68,522 pregnancies, the 1,020 women who used ginger showed no increased risk of congenital malformations, stillbirth or perinatal death, preterm birth, low birth weight, or low Apgar score. That is reassuring, but an observational cohort is not a randomized safety trial. Pregnancy trials generally used about 1 gram of powdered ginger a day for a few days to a few weeks; larger amounts and longer use have not been studied. Very little is known about ginger while breastfeeding. Talk to your doctor or midwife before using it regularly, especially near your due date or if you take an anticoagulant. And if you cannot keep food or fluids down, are losing weight, or are vomiting many times a day, see a clinician instead of self-treating.

How much is too much

No established limit for ginger tea; no trial has tested it by the cup. Trials of powdered ginger generally used 0.5 to 2 grams a day, most often about 1 gram, for days to weeks. Two or three cups of tea daily is a common habit unlikely to harm a healthy adult, but that is a judgment about ordinary use, not a tested safe dose.