Who Must Not Eat Garlic? Essential Health Precautions

November 22, 2025 •

4 min read

According to a study published in the National Institutes of Health, garlic supplements can increase the risk of bleeding, making it dangerous for individuals on blood thinners. While praised for its health benefits, not everyone should eat garlic, especially those with pre-existing conditions or upcoming medical procedures. Understanding the contraindications is crucial for safe consumption.

Quick Summary

This article explores the specific health conditions, medications, and circumstances where garlic consumption should be avoided or limited. It details the risks for individuals with bleeding disorders, digestive problems, and those on certain medications, along with considerations for pregnancy and before surgery.

Key Points

Blood Thinners: Avoid garlic and its supplements if taking blood thinners like warfarin to prevent dangerous bleeding risks.
Pre-Surgery: Stop eating garlic at least two weeks before any scheduled surgery due to its anti-clotting properties.
Digestive Issues: Individuals with GERD, IBS, ulcers, or gastritis should limit or avoid garlic, especially raw, as it can worsen symptoms.
Low Blood Pressure: People with hypotension should use caution, as garlic can further lower blood pressure, causing dizziness.
Allergies: Anyone with a known garlic allergy or sensitivity to other Allium plants should avoid consumption entirely.
Pregnancy: While moderate amounts in food are fine, pregnant women should avoid high supplemental doses of garlic to minimize bleeding risks, especially during delivery.
Liver Disease: Individuals with liver problems should be cautious, as some sources suggest excessive garlic could impact liver function.

Health Conditions That Require Caution with Garlic

Garlic's powerful compounds, while beneficial for many, can be problematic for certain individuals. One of the most critical groups who must not eat garlic includes those with bleeding disorders or those on anticoagulant medications. The active compounds, such as allicin, possess antithrombotic properties, which means they inhibit blood clot formation. This can increase the risk of excessive bleeding, especially when combined with prescription blood thinners like warfarin.

Digestive System Sensitivities

For many, garlic is a cause of significant digestive discomfort. People with conditions affecting the gastrointestinal (GI) tract often find that garlic exacerbates their symptoms. This is due to several factors:

GERD and Acid Reflux: Garlic can relax the lower esophageal sphincter, the muscle that prevents stomach acid from flowing back into the esophagus. This relaxation can trigger or worsen heartburn and acid reflux symptoms.
IBS and Fructan Intolerance: Garlic contains fructans, a type of carbohydrate that can be difficult to digest for individuals with Irritable Bowel Syndrome (IBS) or fructan intolerance. Symptoms commonly include bloating, gas, stomach pain, and general digestive distress.
Gastritis and Ulcers: The potent compounds in raw garlic can irritate the mucous membrane of the stomach and intestines. For those with gastritis or ulcers, this can lead to abdominal pain and a worsening of their condition. While aged garlic extract may have gastroprotective effects in some studies, general garlic consumption should be approached with caution.

Blood Pressure and Circulation Concerns

Garlic is known for its ability to lower blood pressure, which is beneficial for many with hypertension. However, this same effect makes it dangerous for individuals with low blood pressure (hypotension). For these people, eating garlic can cause dizziness, lightheadedness, or even fainting by lowering their blood pressure further.

Medical Procedures and Medications

Surgical Procedures

Anyone with scheduled surgery should stop consuming high doses of garlic or garlic supplements at least two weeks beforehand. Its blood-thinning properties can prolong bleeding during and after the procedure, posing a serious risk. A case report cited an association between high garlic intake and a spontaneous spinal epidural hematoma, reinforcing the need for caution before surgery.

Medication Interactions

Garlic can interact with various medications, affecting their efficacy or increasing side effects.

Blood Thinners: As mentioned, the combination of garlic and anticoagulants like warfarin can dangerously increase the risk of bleeding.
HIV/AIDS Medications: Garlic has been shown to potentially decrease the absorption and effectiveness of certain HIV/AIDS drugs, such as saquinavir.
Blood Pressure Medications: Combining garlic with antihypertensive drugs could cause blood pressure to drop too low, especially in individuals prone to low blood pressure.

Table: Garlic Risks Comparison


Condition / Factor	Primary Risk Associated with Garlic	Recommended Precaution
Taking Blood Thinners (e.g., Warfarin)	Increased risk of bleeding or bruising due to enhanced anticoagulant effect.	Avoid garlic supplements and limit dietary intake; consult doctor before use.
Gastroesophageal Reflux Disease (GERD)	Worsened heartburn and acid reflux due to relaxation of the esophageal sphincter.	Limit or avoid garlic, especially raw; choose cooked garlic if tolerated.
Irritable Bowel Syndrome (IBS)	Triggering of bloating, gas, and stomach pain due to high fructan content.	Consider a low-FODMAP diet and limit garlic intake; monitor symptoms.
Hypotension (Low Blood Pressure)	Further reduction of blood pressure, potentially causing dizziness and fainting.	Consume in very small, monitored amounts; consult doctor if experiencing symptoms.
Upcoming Surgery	Increased bleeding risk during and after the procedure.	Stop taking garlic supplements and high dietary amounts at least two weeks prior.
Pregnancy/Breastfeeding	Potential for heartburn or affecting milk taste; supplements can increase bleeding risk.	Moderate intake via food is likely safe, but avoid high supplemental doses; consult a doctor.

Other Considerations and Special Groups

Allergies

While uncommon, garlic allergies can occur. Symptoms can range from skin rashes and itching to more severe reactions like asthma and anaphylaxis. Those with an allergy or sensitivity to other Allium family members, such as onions or leeks, may also be sensitive to garlic.

Pregnancy and Breastfeeding

For pregnant women, moderate consumption of garlic in food is generally considered safe. However, high supplemental doses should be avoided due to the potential increased risk of bleeding, especially during delivery. During breastfeeding, some studies suggest that maternal garlic consumption can affect the odor and flavor of breast milk, potentially influencing the infant's feeding.

Liver Disease

According to some traditional medicine sources, those with liver disease should be cautious with garlic. The bioactive compounds may overstimulate the liver, and excessive consumption could be a concern for individuals with impaired liver function. However, evidence is limited, and it is best to consult a healthcare professional.

Conclusion

While garlic holds a strong reputation as a healthy ingredient and natural remedy, it is not suitable for everyone. Individuals on blood thinners, preparing for surgery, or managing conditions like GERD, IBS, or low blood pressure must not eat garlic in high concentrations, particularly in supplement form. Moderation is key for many, and for others, avoidance is the safest approach. The key takeaway is to be mindful of your specific health profile and consult a healthcare provider before making significant dietary changes or using garlic supplements, especially if you have underlying health issues.

For further information on the medicinal properties of garlic, you can consult sources such as the National Center for Complementary and Integrative Health.

Frequently Asked Questions

Yes, garlic has natural blood-thinning properties that can increase the effects of anticoagulant medications like warfarin, raising the risk of excessive bleeding or bruising.

No, it is generally not safe for people with acid reflux or GERD. Garlic can relax the lower esophageal sphincter, allowing stomach acid to flow back into the esophagus and worsening symptoms like heartburn.

Yes, it is highly recommended to stop consuming garlic or garlic supplements at least two weeks before any scheduled surgery to reduce the risk of excessive bleeding during and after the procedure.

Garlic can lower blood pressure. For individuals already diagnosed with hypotension, consuming garlic can cause blood pressure to drop to dangerously low levels, leading to dizziness or fainting.

Moderate amounts in food are usually safe during pregnancy, but high supplemental doses should be avoided due to increased bleeding risk. During breastfeeding, it can alter the flavor of breast milk, which may affect an infant's feeding.

Yes, though uncommon, garlic allergies can occur. Reactions can include skin rashes, itching, and digestive issues. In rare cases, severe reactions like anaphylaxis are possible.

For individuals with IBS, especially those with fructan intolerance, garlic can trigger digestive issues such as bloating, gas, and stomach pain due to its high fructan content.

Raw garlic is more potent and can cause more significant digestive irritation and heartburn for sensitive individuals. Cooking garlic may reduce some of its adverse digestive effects.