Who Should Not Drink Barley Grass? A Guide to Precautions and Side Effects

November 24, 2025 •

4 min read

While celebrated as a nutrient-dense superfood, barley grass is not suitable for everyone, with specific health conditions requiring caution or complete avoidance. This is because it can interact with medications, exacerbate existing illnesses, and trigger adverse reactions in sensitive individuals. Understanding who should not drink barley grass is crucial for ensuring safety and preventing unintended health complications.

Quick Summary

This guide details the specific health conditions, medication interactions, and contraindications that indicate when individuals should avoid barley grass supplements. It covers risks for those with celiac disease, kidney issues, diabetes, and during pregnancy or breastfeeding, while emphasizing the importance of professional medical advice.

Key Points

Celiac Disease: Individuals must avoid barley grass unless it is a certified gluten-free product, due to a high risk of cross-contamination with gluten from the grain.
Kidney Disease: High potassium levels in barley grass can be dangerous for those with impaired kidney function, potentially leading to serious heart problems.
Blood Thinners: The high Vitamin K content can counteract the effects of blood-thinning medication, like warfarin, leading to an increased risk of blood clots.
Diabetes: Diabetics on medication should be cautious, as barley grass can lower blood sugar and risk hypoglycemia if not properly monitored and managed.
Pregnancy and Breastfeeding: There is insufficient safety information available, so it is recommended to avoid barley grass supplements during these periods.
Digestive Issues: Sudden high intake can cause side effects like bloating, gas, or diarrhea, so a gradual introduction is advised.
Gout Patients: While some effects may be beneficial, individual reactions to uric acid levels can vary, so it is best to consult a doctor.

Understanding the Risks of Barley Grass Consumption

Despite its reputation as a beneficial superfood, barley grass carries specific risks for certain populations. These considerations are critical and should not be overlooked, particularly for individuals managing pre-existing health conditions or taking certain medications. Consulting a healthcare provider before adding any new supplement to your diet is always the safest course of action.

Celiac Disease and Gluten Sensitivity

One of the most important contraindications for barley grass is celiac disease or gluten sensitivity. While barley grass, harvested from the young plant before it develops grain, is inherently gluten-free, there is a significant risk of cross-contamination.

Risk of cross-contamination: If a product is not certified gluten-free, it is highly likely that trace amounts of gluten from the barley grain have contaminated the grass during harvesting or processing.
Hypersensitivity reactions: Individuals with a known allergy to cereal grains may also experience an allergic reaction to barley grass, even without gluten. Symptoms can include itching, swelling, or breathing difficulties.
How to stay safe: Always choose products explicitly labeled with a "certified gluten-free" stamp from a trusted third party.

Kidney Disease Patients

Barley grass supplements often contain high levels of potassium, which can pose a significant danger to individuals with kidney disease, especially chronic kidney disease (CKD).

Potassium content: Healthy kidneys excrete excess potassium. When kidney function is impaired, high levels of potassium can build up in the blood, leading to a condition called hyperkalemia.
Symptoms of hyperkalemia: This can cause serious health issues, including irregular heart rhythms, muscle weakness, and, in severe cases, heart failure.
Nephrology expert warning: Nephrologists caution that relying on barley water or other barley products as a cure for CKD is a myth and can be life-threatening for patients on dialysis who must restrict fluid intake.

Individuals on Blood Thinners (Warfarin)

Barley grass is rich in Vitamin K, a nutrient that plays a vital role in blood clotting. This can cause a dangerous interaction with blood-thinning medications like warfarin.

Mechanism of action: Warfarin works by inhibiting Vitamin K-dependent clotting factors. A sudden increase or decrease in Vitamin K intake can alter the medication's effectiveness, potentially leading to dangerous bleeding or blood clots.
Consistency is key: Patients on warfarin must maintain a consistent Vitamin K intake. The addition of a high-dose barley grass supplement can disrupt this balance.
Professional guidance: Anyone taking anticoagulant medications must consult their doctor before consuming barley grass to avoid life-threatening complications.

Diabetes Management and Hypoglycemia

While some research indicates that barley grass may help regulate blood sugar, this effect can be problematic for individuals with diabetes, particularly those on insulin or other blood sugar-lowering medications.

Blood sugar-lowering effect: The high fiber content of barley grass can slow sugar absorption, potentially leading to dangerously low blood sugar levels (hypoglycemia) when combined with diabetes medication.
Medication adjustment: A healthcare provider may need to adjust diabetes medication dosages to safely incorporate barley grass, and blood sugar should be monitored closely.

Pregnancy and Breastfeeding

There is a lack of reliable scientific information regarding the safety and effects of barley grass supplements during pregnancy and lactation. Due to this uncertainty, medical professionals advise caution.

Limited research: Information on how high concentrations of barley grass supplements affect a developing fetus or nursing infant is insufficient.
Moderation is advised: While barley grains found in food are generally considered safe, concentrated forms in supplements are not.
Seek medical advice: Pregnant and breastfeeding women should avoid barley grass supplements or seek professional medical advice before use.

Potential Side Effects and Digestive Issues

Aside from specific medical conditions, even healthy individuals may experience side effects, particularly when first introducing barley grass into their diet.

High fiber content: The supplement's high fiber can lead to bloating, gas, stomach cramps, or loose stools, especially if intake is increased too quickly.
Gradual introduction: To minimize digestive upset, it is recommended to start with a small amount (e.g., 1–2g) and gradually increase the dosage over time, allowing the body to adjust.

Comparison Table: Barley Grass Contraindications


Condition / Medication	Reason for Caution or Avoidance	Key Risk Factor	Safe Alternative / Action	Recommended Specialist Consultation
Celiac Disease	Risk of gluten cross-contamination during processing.	Hidden gluten can trigger severe autoimmune reactions.	Certified gluten-free supplements or different superfood.	Gastroenterologist
Kidney Disease	High potassium content can cause hyperkalemia.	Impaired kidney function leads to toxic potassium buildup.	Strictly manage potassium and fluid intake per doctor's orders.	Nephrologist
Taking Warfarin	High Vitamin K content interferes with blood thinner.	Altered clotting time can cause dangerous bleeding or clots.	Maintain consistent Vitamin K intake as directed.	Cardiologist, GP
Diabetes (on medication)	Potential for significant blood sugar drops.	Hypoglycemia risk when combined with blood sugar medication.	Close monitoring and dosage adjustment by a doctor.	Endocrinologist, GP
Pregnancy/Lactation	Lack of sufficient research on safety.	Unknown effects on the fetus or breastfed infant.	Avoid or consult a healthcare professional.	OB-GYN
Gout	Possible impact on uric acid levels; insufficient evidence.	Some studies show benefit, but individual reactions can vary.	Discuss with a doctor before use, especially during flares.	Rheumatologist

Conclusion: Prioritizing Health Over Trends

Barley grass is a nutritious green supplement with documented benefits for many. However, its suitability is not universal. For those with conditions like celiac disease, chronic kidney issues, diabetes requiring medication, or those taking blood thinners, the risks may outweigh the potential rewards. Furthermore, a lack of research warrants a cautious approach during pregnancy and breastfeeding. Individuals with sensitive digestive systems should also introduce it slowly to mitigate discomfort. Ultimately, a personalized approach to health is always best, guided by a medical professional, to ensure supplements like barley grass enhance, rather than harm, your well-being.

Frequently Asked Questions

Barley grass is not safe for someone with celiac disease unless it is explicitly certified as gluten-free. There is a high risk of cross-contamination with the barley grain during processing, which contains gluten and can trigger a severe autoimmune reaction.

No, if you have kidney disease, especially chronic kidney disease (CKD), you should not take barley grass supplements without a doctor's supervision. They contain high levels of potassium, which damaged kidneys cannot effectively filter, leading to dangerous hyperkalemia.

Yes, barley grass can interact with blood thinner medications like warfarin. Its high Vitamin K content affects blood clotting and can reduce the medication's effectiveness, which could increase the risk of dangerous blood clots.

No, pregnant and breastfeeding women should avoid barley grass supplements. There is a lack of reliable scientific research confirming its safety for a developing fetus or nursing infant.

For people with diabetes, barley grass can cause issues because it may significantly lower blood sugar levels. This can interfere with diabetes medications and cause a dangerous drop in blood sugar (hypoglycemia).

Yes, some healthy individuals may experience digestive issues such as bloating, gas, or diarrhea, particularly when first introducing barley grass due to its high fiber content. Starting with a small dose and increasing gradually can help mitigate these effects.

While some sources suggest potential benefits for gout due to anti-inflammatory properties, individual reactions can vary, and there is no conclusive clinical evidence. You should consult a rheumatologist before using it to manage your condition.