Who Should Not Drink Onion Tea and Why

December 30, 2025 •

3 min read

While many praise onion tea for its potential health benefits, it's not a safe or suitable remedy for everyone. Certain individuals, particularly those with pre-existing health conditions or sensitivities, should avoid this herbal concoction to prevent adverse effects.

Quick Summary

A guide detailing the specific health conditions and medications that contraindicate drinking onion tea, including allergies, digestive problems, blood disorders, and diabetes concerns.

Key Points

Blood Thinners: Individuals taking anticoagulant medications like warfarin should not drink onion tea due to the risk of increased bleeding.
Digestive Issues: People with Irritable Bowel Syndrome (IBS) or sensitive stomachs should avoid onion tea as its high FODMAP content can trigger gas, bloating, and heartburn.
Diabetic Patients: Onion tea may lower blood sugar, creating a risk of hypoglycemia for individuals with diabetes, especially those on medication.
Allergy Sufferers: Anyone with a known allergy to onions, or related plants, should avoid onion tea completely to prevent allergic reactions.
Before Surgery: Stop consuming onion tea at least two weeks before any scheduled surgery to minimize the risk of bleeding and interference with blood sugar levels.
Pregnancy and Breastfeeding: The medicinal use of onion tea during pregnancy and breastfeeding is not sufficiently studied and should be avoided.
Liver Metabolism: Onion tea could interfere with how the liver processes certain medications, potentially altering their effects.

Underlying Health Conditions to Consider

For most people, consuming onions as a food ingredient is perfectly safe. However, concentrating the compounds in a tea-like form can amplify their effects, making it a risk for certain individuals. This is especially true for those with pre-existing medical issues.

Allergies and Sensitivities

Even though uncommon, some people can have a true allergy to onions, which can manifest in a range of symptoms from mild to severe. A skin rash, hives, or even a more serious asthmatic reaction can occur. Individuals with sulfur allergies may also experience an adverse reaction to onions. People with known allergies to related plants, like garlic, leeks, or celery, could also have a cross-allergic sensitivity to onions.

Irritable Bowel Syndrome (IBS) and Digestive Distress

Onions contain poorly absorbed carbohydrates known as FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols). For individuals with IBS or other sensitive digestive systems, a concentrated dose from onion tea can trigger significant abdominal discomfort, gas, and bloating.

Gas and Bloating: The fermentable carbohydrates can lead to excess gas production.
Heartburn: Onions, particularly when raw or concentrated in a tea, can exacerbate or trigger symptoms of heartburn or gastroesophageal reflux disease (GERD).
Other GI upset: Nausea, vomiting, and diarrhea have been reported with excessive onion consumption.

Medical Treatments and Procedures

Beyond general health, certain medications and upcoming medical procedures can make onion tea a risky choice due to potential interactions and side effects.

Blood-Thinning Medications and Bleeding Disorders

Onions have natural anticoagulant properties, meaning they can slow down blood clotting. This is particularly dangerous for individuals on blood-thinning medications like warfarin or clopidogrel. Drinking onion tea could significantly increase the risk of bruising and bleeding. For this reason, anyone with a known bleeding disorder should also strictly avoid medicinal amounts of onion.

Diabetes and Blood Sugar Control

Some research suggests that concentrated onion extracts can lower blood sugar levels. While this might sound beneficial, it can be hazardous for people with diabetes, especially those taking anti-diabetic medications like insulin or glimepiride. The combination could cause blood sugar levels to drop too low, leading to hypoglycemia.

Upcoming Surgery

Because of its effects on blood clotting and blood sugar, onion tea should be avoided for at least two weeks before any scheduled surgical procedure. It could increase the risk of bleeding during or after the surgery and interfere with blood sugar control.

Comparison of Risks by Health Group


Health Group	Primary Risk from Onion Tea	Mechanism of Risk	Recommended Action
Individuals with IBS	Digestive upset (gas, bloating, heartburn)	High FODMAP content ferments in the gut.	Avoid onion tea, especially during flare-ups.
People on Blood Thinners	Increased bleeding and bruising	Anticoagulant properties interfere with medication.	Do not drink; consult a doctor about dietary restrictions.
Diabetic Patients	Dangerously low blood sugar (hypoglycemia)	Concentrated onion can lower blood glucose levels.	Monitor blood sugar and consult a doctor before use.
Pregnant/Breastfeeding Women	Lack of safety data; potential GI issues	Insufficient research on high-dosage effects.	Stick to culinary amounts; avoid medicinal doses.
Individuals with Allergies	Allergic reaction (hives, asthma)	Immune system reacts to allergenic compounds.	Avoid completely if allergic to onions or related plants.

Pregnancy and Breastfeeding

While small, culinary amounts of onion are typically considered safe during pregnancy and breastfeeding, there is not enough reliable research to determine the safety of medicinal, concentrated amounts found in onion tea. It is always best for pregnant and breastfeeding individuals to consult a healthcare provider and err on the side of caution. Some pregnant women also experience heightened heartburn, which onion tea could worsen.

Conclusion: Consult Your Doctor Before Trying Onion Tea

Onion tea is not a one-size-fits-all remedy. While it may be harmless for some, it poses significant risks for individuals with specific medical conditions, those on certain medications, and during pregnancy. The concentrated nature of the tea amplifies the potential for adverse effects, from digestive distress to dangerous drug interactions. It is always recommended to speak with a healthcare professional before incorporating any new herbal remedy into your routine, especially if you have an existing health concern. For general health, it's safer and more effective to stick to consuming onions in regular food amounts rather than as a concentrated tea. For an authoritative resource on supplement interactions, consult reputable medical sites such as WebMD.

Frequently Asked Questions

No, if you are prone to heartburn or have gastroesophageal reflux disease (GERD), you should avoid onion tea. Concentrated onion can cause the esophageal sphincter to relax and irritate the stomach lining, worsening your symptoms.

There is a lack of reliable information about the safety of large, medicinal amounts of onion tea for pregnant or breastfeeding women. It is safest to avoid it and stick to normal food amounts of onion after consulting a healthcare provider.

Diabetic individuals should be very cautious with onion tea and monitor their blood sugar closely. High doses of onion can lower blood glucose, and when combined with diabetes medication, this could lead to dangerously low blood sugar levels (hypoglycemia).

Yes, onion tea can interact with blood-thinning medications (anticoagulants) and anti-diabetic drugs. It can also interfere with certain medications processed by the liver.

While rare, individuals with a known allergy to onions or related plants like garlic and celery are at risk. An allergic reaction can include skin rashes or asthmatic events.

Onion tea can slow blood clotting and lower blood sugar. To avoid complications with bleeding or blood sugar control during and after a procedure, it should be stopped at least two weeks prior to any surgery.

Even in healthy individuals, excessive consumption of onion tea may cause stomach pain, gas, and heartburn. Those with sensitive stomachs are at a higher risk for these side effects.