Are there any side effects of celery?

December 12, 2025 •

4 min read

Celery, a crisp and hydrating vegetable enjoyed in many diets, is generally considered safe for most people in moderate amounts. However, a range of potential side effects, from mild digestive upset to severe allergic reactions and medication interactions, can affect sensitive individuals or those consuming large quantities.

Quick Summary

Despite its healthy image, celery poses risks like allergic reactions, digestive discomfort, and photosensitivity. Individuals on certain medications, pregnant women, and those with specific health conditions should exercise caution before consuming celery.

Key Points

Allergic Reactions: Celery is a common allergen, potentially causing mild Oral Allergy Syndrome or, in rare cases, life-threatening anaphylaxis.
Photosensitivity: Compounds in celery called psoralens can cause skin to become highly sensitive to sunlight, leading to rashes and blisters, particularly after direct contact.
Medication Interactions: Celery can affect the potency of medications for blood pressure, thyroid conditions, and blood thinning, making medical supervision important if you are on these drugs.
Gastrointestinal Issues: High fiber and FODMAP content can cause bloating, gas, and diarrhea, especially for individuals with sensitive digestive systems or IBS.
Pregnancy Concerns: Celery seed and oil in large, medicinal doses can be unsafe for pregnant women due to uterine stimulant properties that could induce miscarriage.
Moderation is Key: Consuming excessive amounts, particularly of celery juice, can lead to overexposure to pesticides (if not organic) and nutrient imbalances due to its low-calorie, high-water content.

Common Side Effects of Celery

While a nutritious vegetable, celery can lead to adverse effects in some individuals. These range from common digestive issues to more serious allergic responses.

Allergic Reactions

Celery is a known allergen, and reactions can range from mild to life-threatening. Symptoms can appear within minutes to hours after ingestion or even contact with the skin.

Oral Allergy Syndrome (OAS): Mild symptoms localized to the mouth, such as itching, tingling, or swelling of the lips, tongue, and throat, can occur due to cross-reactivity with birch or mugwort pollen. Cooking celery often denatures the protein responsible for this reaction.
Severe Systemic Reactions: In more serious cases, a celery allergy can trigger anaphylaxis, a severe, potentially fatal reaction. Symptoms include difficulty breathing, swelling of the face and throat, hives, and a sudden drop in blood pressure. Individuals with a severe celery allergy should avoid all celery and products containing it.

Digestive Discomfort

For some people, especially when consumed in large amounts, celery can cause gastrointestinal issues.

Bloating and Gas: Celery contains mannitol, a type of sugar alcohol that can be difficult for some people to digest. This can lead to fermentation in the large intestine, causing bloating and gas.
Irritable Bowel Syndrome (IBS): The high fiber and FODMAP content in celery can exacerbate symptoms for those with IBS or other sensitive digestive systems. Moderating intake and ensuring adequate hydration can help mitigate these effects.

Photosensitivity (Sun Sensitivity)

Celery, particularly the seeds, leaves, and plants infected with pink rot fungus, contains compounds called psoralens. These are phototoxic, meaning they can cause skin inflammation and sensitivity to sunlight.

Phytophotodermatitis: This is a skin reaction that occurs when psoralens from celery residue on the skin are exposed to UV light. It can lead to redness, blistering, and pain, with the resulting hyperpigmentation sometimes lasting for months.
Increased Risk: Workers who regularly handle celery, such as pickers and grocery store staff, are at a higher risk of developing this condition. For the general public, the risk from eating celery is very low unless excessive amounts are ingested before sun or tanning bed exposure.

Celery's Potential Drug and Health Interactions

Due to its active compounds, celery can interact with various medications and is not suitable for certain health conditions. Always consult a healthcare provider before using celery in medicinal amounts or as a supplement.

Medication Interactions

Blood Thinners (Anticoagulants): Celery, especially the root, contains compounds that may slow blood clotting. This can increase the risk of bleeding and bruising when taken with anticoagulant and antiplatelet drugs like warfarin, aspirin, and clopidogrel.
High Blood Pressure Medications: Celery has been shown to lower blood pressure. Taking celery seed extract alongside antihypertensive drugs could cause blood pressure to drop too low.
Thyroid Medications: Celery might interfere with thyroid function. Individuals with high or low thyroid levels or those on medication like levothyroxine should be cautious, as celery seed might reduce the medication's effectiveness. There are also reported cases of celery extract causing hyperthyroidism.
Lithium: Celery can decrease how efficiently the body clears lithium, leading to increased lithium levels and potential side effects.
Photosensitizing Drugs: Combining celery with medications that also increase sun sensitivity can heighten the risk of sunburn or rashes.

Conditions of Concern

Pregnancy and Breastfeeding: Celery oil and seeds in medicinal amounts are considered unsafe during pregnancy as they can stimulate the uterus and increase miscarriage risk. While food amounts are typically fine, high doses should be avoided. The safety of celery seeds during breastfeeding is not well-established.
Kidney Issues: Individuals with kidney inflammation or kidney disorders should avoid consuming celery in medicinal amounts, as it may exacerbate their condition. However, regular food amounts are generally considered safe and may even be beneficial for kidney health in healthy individuals.
Bleeding Disorders: Due to its potential to slow blood clotting, celery root should be avoided in medicinal amounts by anyone with a bleeding disorder.

Table: Risks of Various Celery Forms


Celery Form	Primary Risks	Notes
Celery Stalks (Moderate Amount)	Digestive discomfort (bloating, gas) in sensitive individuals, low risk of photosensitivity	Generally safe for most; moderation is key.
Celery Stalks (Excessive Amount)	Nutrient deficiencies, potential for increased pesticide exposure if not organic, risk of digestive upset	The very low-calorie content can lead to insufficient nutrient intake if relied upon too heavily.
Celery Juice	Concentrated pesticides (if not organic), high oxalate intake potentially leading to kidney stones, intensified digestive issues in some	Stripped of fiber, juices deliver concentrated compounds that can be problematic in large quantities.
Celery Seeds / Extract	Drug interactions, uterine stimulation (unsafe for pregnancy), photosensitivity	Psoralens are more concentrated here, increasing risk of sun sensitivity and other medicinal-level effects.

Conclusion: A Balanced Approach to Celery

For most people, celery is a safe, crunchy, and hydrating vegetable that offers beneficial nutrients and antioxidants. The key to avoiding most side effects lies in moderation and being mindful of your body's specific sensitivities. Allergies are a significant concern for a subset of the population and require strict avoidance. Those with pre-existing conditions involving the kidneys, thyroid, or blood clotting, as well as pregnant women, should consult a doctor before increasing their celery intake, especially when considering concentrated forms like extracts or seeds. Choosing organic celery can help minimize pesticide exposure, though thorough washing is always recommended. By understanding the potential risks and listening to your body, you can safely incorporate celery into a well-rounded and varied diet.

Frequently Asked Questions

Yes, celery can cause allergic reactions ranging from mild oral allergy syndrome (tingling or itching of the mouth) to severe anaphylaxis, which requires immediate medical attention.

Yes, celery can cause bloating and gas, particularly when consumed in large amounts. It contains mannitol, a sugar alcohol that can be difficult for some people to digest, leading to digestive discomfort.

Yes, celery contains phototoxic compounds called psoralens. For some, especially after handling the plant or consuming large quantities, sun exposure can cause skin inflammation and blistering, a condition called phytophotodermatitis.

Individuals with celery allergies should avoid it entirely. People with bleeding disorders, thyroid conditions, kidney inflammation, or those who are pregnant should be cautious and consult a doctor before consuming celery in medicinal amounts.

Celery can interact with several types of medication. It may interfere with blood thinners, cause blood pressure to drop too low alongside antihypertensive drugs, and potentially affect thyroid function.

Celery juice can be more problematic than whole celery for some individuals. It concentrates natural compounds like psoralens and oxalates, potentially increasing the risk of photosensitivity or kidney stone formation in susceptible individuals.

While consuming food amounts of celery is generally safe during pregnancy, medicinal quantities from concentrated seeds or oils should be avoided. High doses may stimulate the uterus and increase the risk of miscarriage.

Organic celery is a safer choice because conventional celery often ranks high in pesticide residues. Choosing organic reduces exposure to these chemicals, and thoroughly washing all celery is always recommended.