Drinking moldy tea is unlikely to cause serious harm for most people. A single exposure typically results in no symptoms at all, or at worst, mild nausea and an upset stomach that passes within a day. The real risks depend on how much mold was present, what type it was, and whether you have a mold allergy or weakened immune system.
What Most People Experience
If you took a sip of tea and then noticed mold floating in it, the most likely outcome is nothing. Your stomach acid is effective at neutralizing small amounts of mold, and your body treats it much like any other unwanted substance in food. Some people experience mild gastrointestinal symptoms: a wave of nausea, a brief episode of vomiting, or loose stools. These typically resolve on their own within a few hours.
A reaction can be immediate or delayed, and many people develop no symptoms whatsoever. The more mold present, the more likely you are to notice something. A cup of tea with a thin film of surface mold is different from drinking a deeply contaminated brew you left sitting out for days.
When Mold Allergies Complicate Things
If you have a mold allergy, your body may overreact to even a small exposure. Common mold allergy symptoms mirror those of hay fever: sneezing, a runny or stuffy nose, itchy and watery eyes, and a scratchy throat. These can show up quickly or develop over the following hours.
For people with both a mold allergy and asthma, the reaction can be more serious. Mold spore exposure can trigger wheezing, chest tightness, shortness of breath, and coughing fits. In rare cases, this can escalate into a full asthma attack. If you have asthma and start experiencing breathing difficulty after drinking moldy tea, treat it as you would any asthma flare-up and use your rescue inhaler.
The Concern With Mycotoxins
Certain molds produce toxic byproducts called mycotoxins, and these are the real health concern with contaminated food and beverages. Tea leaves can harbor molds from the Aspergillus, Penicillium, and Fusarium families, some of which produce toxins that affect the liver and kidneys over time. The most studied of these in tea are aflatoxins and ochratoxin A.
Here’s what matters for a one-time exposure: regulatory testing of commercial teas consistently finds toxin levels well below safety thresholds. Countries set limits at around 5 to 10 micrograms per kilogram of tea for the most dangerous of these toxins. In large studies of commercial tea samples, the vast majority fall within safe ranges. A single cup of moldy tea, even one with visible growth, would expose you to a tiny fraction of what’s considered a concerning dose. The cancer and organ damage risks associated with mycotoxins come from chronic, repeated exposure over months and years, not a one-time accidental sip.
Boiling Water Doesn’t Solve the Problem
You might wonder whether brewing temperature kills the mold and makes everything safe. Boiling water at 100°C (212°F) does kill active mold growth, but it doesn’t destroy mycotoxins that have already been produced. These toxins are heat-stable compounds that survive brewing temperatures intact. So if your tea leaves were already moldy before you brewed them, the toxins would still be present in the water even after steeping. This is why prevention matters more than treatment: once mold has grown and produced toxins, you can’t cook them away.
Who Faces Greater Risk
Most healthy adults can handle an accidental mold exposure without any lasting effects. The people who face real danger are those with weakened immune systems, including people undergoing chemotherapy, organ transplant recipients on immunosuppressive drugs, and those with HIV/AIDS. For these individuals, certain molds (particularly Aspergillus species) can cause invasive infections that spread beyond the digestive tract into the lungs and bloodstream. These infections are rare but serious, and symptoms include persistent fever, cough that produces blood, chest pain, and chills.
People with chronic lung conditions like cystic fibrosis or severe asthma are also more vulnerable. A condition called allergic bronchopulmonary aspergillosis can develop when Aspergillus spores trigger a strong inflammatory reaction in the lungs, leading to worsening breathing problems and a cough that may bring up blood or mucus.
How Brewed Tea Goes Bad
Understanding how tea becomes moldy helps you avoid it in the future. Brewed tea left at room temperature stays safe for roughly 8 hours, though flavor starts declining after 4 to 6 hours. Beyond that window, bacteria and mold begin colonizing the warm, moist, nutrient-rich liquid. Refrigerated brewed tea lasts 24 to 48 hours before quality drops off.
The visible mold you see on old tea, usually a fuzzy white, green, or black layer on the surface, represents a mature colony. By the time mold is visible, it has been growing and potentially producing mycotoxins for some time. The rule of thumb is simple: if your brewed tea has been sitting out overnight, or has been in the fridge for more than two days, discard it. If you see any film, cloudiness, or fuzzy spots, don’t drink it.
Dry tea leaves can also develop mold if stored in humid conditions. Tea should be kept in airtight containers away from moisture. If your loose-leaf tea or tea bags smell musty, look clumped together, or show visible discoloration, toss them.
Symptoms That Warrant Attention
For most people, a single sip of moldy tea requires nothing more than rinsing your mouth and discarding the cup. But certain symptoms after exposure suggest something more than a routine reaction. Persistent shortness of breath, wheezing that doesn’t respond to an inhaler, a high fever, or any sign of a severe allergic reaction (swelling of the throat, widespread hives, difficulty swallowing) should be evaluated promptly. If you have a compromised immune system and develop a fever or respiratory symptoms in the days following exposure, that also warrants medical evaluation, since invasive mold infections can take time to develop and need early treatment.