Rooibos Tea

Safety, side effects & who should avoid it

For most healthy adults, rooibos at ordinary tea strength appears low-risk, and it contains no caffeine. Three things are worth knowing. A small number of case reports link rooibos-containing tea to liver injury, though causation is not established. Laboratory work shows rooibos compounds can both inhibit and potentially induce drug-metabolizing enzymes, which makes interactions hard to predict in either direction. And there is no authoritative monograph to fall back on — as of this writing rooibos has no entry in NIH's LiverTox database, NCCIH's Herbs at a Glance, or MedlinePlus. What follows is built from a few case reports and laboratory studies, not from a formal safety review.

Who should avoid it

• Anyone with liver disease or unexplained raised liver enzymes. Three published case reports describe hepatitis-like liver injury in people drinking rooibos. Causation is not established, and in the biopsy-confirmed case — a 52-year-old man — the tea was a blend of rooibos and buchu, so rooibos alone may not have been responsible. Millions of people drink rooibos without trouble. But if your liver is already under strain, this is an easy thing to skip.
• Transplant recipients taking tacrolimus. A 2025 review of food-drug interactions lists rooibos among products that may reduce tacrolimus bioavailability, apparently through CYP450 induction and the P-glycoprotein efflux pump. Lower tacrolimus levels could put a graft at risk. Don't drink it without your transplant team's approval.
• People on narrow-therapeutic-index drugs such as warfarin, some anti-seizure medicines, or immunosuppressants. Rooibos extracts inhibit CYP2C9, CYP2C19 and CYP3A4 in laboratory assays, and rooibos compounds also activate PXR, which can push some of the same enzymes the other way. The net effect in a person has never been measured, so ask a pharmacist first.
• Infants and young children. Rooibos is traditionally given to colicky babies in South Africa, but that use has never been tested in a trial, and rooibos safety has not been studied in infants at all. Herbal tea should never replace breast milk or formula. Ask a pediatrician before giving rooibos to a baby or a young child.
• Anyone taking corticosteroids, or being treated for a hormone-sensitive cancer, should mention rooibos to their doctor. Three compounds isolated from rooibos leaves showed estrogenic activity in a lab assay, and one small human study found that rooibos consumption raised plasma cortisone and lowered the cortisol-to-cortisone ratio. What either finding means clinically is unknown.

Possible side effects

• Most people report none. Rooibos contains no caffeine, so it is unlikely to interfere with sleep.
• Rare reports of liver injury: raised liver enzymes, jaundice, dark urine, fatigue, nausea, and in one report a low platelet count. In the case that included a liver biopsy, liver function recovered after the person stopped drinking the tea.
• See a doctor promptly if you develop yellowing of the eyes or skin, dark urine, pain under the right ribs, or persistent nausea — and tell them you drink rooibos. Herbal teas are easy to overlook as a cause.

Medication interactions

• Tacrolimus: a 2025 narrative review reports that rooibos may reduce tacrolimus bioavailability, apparently via CYP450 induction and the P-glycoprotein efflux pump. This is a review of reported interactions, not a controlled study in patients.
• CYP3A4 substrates: a rooibos leaf-and-stem extract inhibited CYP3A4 (IC50 1.7 µg/mL) along with CYP1A2, CYP2D6, CYP2C9 and CYP2C19. The same study found that aspalathin and nothofagin activated PXR and increased CYP3A4 and CYP1A2 messenger RNA — an induction signal pointing the opposite way. In-vitro data in both directions, not a confirmed clinical interaction.
• Statins and oral diabetes drugs: rooibos extracts inhibited CYP2C8, CYP2C9 and CYP3A4 in enzyme assays — the enzymes that clear atorvastatin, sulfonylureas and thiazolidinediones. No clinical case of this interaction has been published.
• ACE inhibitors: a single serving transiently reduced ACE activity in healthy volunteers. No clinical problem has been reported, but mention regular rooibos drinking to your prescriber.
• Other drugs or supplements that can strain the liver: given the case reports above, it is reasonable to be cautious about drinking large amounts of rooibos alongside them, and to mention it to your prescriber.
• An important caveat on all of the above: these enzyme findings come from concentrated extracts at laboratory concentrations. The authors of one study specifically flagged the risk from a high intake of nutraceuticals containing rooibos extracts, rather than from ordinary brewed tea. Whether a cup of tea ever reaches these concentrations in a person is unknown.

Pregnancy & breastfeeding

No controlled studies have looked at rooibos in pregnancy or breastfeeding. It's caffeine-free and widely drunk by pregnant women in South Africa, which is reassuring but isn't evidence of safety — and lab work has identified compounds in rooibos with estrogenic activity, which nobody has followed up in pregnancy. Keep it to ordinary tea strength, skip extract supplements, and talk to your doctor or midwife first.

How much is too much

No established limit. The most brewed rooibos anyone has been formally studied drinking is six cups a day for six weeks, in a 40-person study that measured liver and kidney function. Concentrated extract capsules deliver far higher flavonoid doses than tea, carry the enzyme-interaction concerns above, and have no long-term safety data behind them.