While often viewed as a healthy and harmless vegetable, celery contains several active phytochemicals that can, in high concentrations, have a significant effect on the body and interfere with various medications. The risk of interaction is minimal for typical food amounts but increases substantially with concentrated forms, such as celery juice, extracts, and supplements. Individuals on certain long-term medications should be particularly mindful of their celery intake.
Interactions with Blood Thinners
One of the most well-documented interactions is with blood-thinning medication. Celery is a source of vitamin K, a nutrient essential for the synthesis of blood-clotting proteins.
- Warfarin (Coumadin): For people on warfarin, maintaining a consistent daily intake of vitamin K is critical for the medication to work effectively. Suddenly consuming a large amount of celery, especially as juice, can increase vitamin K levels and reduce the effectiveness of warfarin, increasing the risk of a blood clot.
- Other Anticoagulants and Antiplatelets: Celery root, particularly in medicinal amounts, may also slow blood clotting on its own. When combined with other blood thinners, such as aspirin, clopidogrel (Plavix), or heparin, it could increase the risk of bruising and bleeding.
Interactions with Blood Pressure Medications
Celery seed extract, in particular, is known to have blood pressure-lowering properties. This can cause an additive effect when combined with prescription antihypertensive drugs.
- Risk of Hypotension: For those taking medications for high blood pressure, such as ACE inhibitors, beta-blockers, or calcium channel blockers, consuming celery seed extract could cause blood pressure to drop too low. This can lead to dizziness, lightheadedness, or fainting.
- Monitoring is Key: Patients taking both celery seed extract and blood pressure medication should monitor their blood pressure closely and discuss it with their healthcare provider.
Interactions with Diuretics (Water Pills)
Celery has natural diuretic properties, meaning it increases urine production to help the body eliminate excess fluid.
- Additive Effect: Taking celery seed alongside prescription diuretics can produce an additive effect. This may increase the risk of dehydration, electrolyte imbalance, and other related complications.
Interactions with Sedatives and CNS Depressants
Celery contains compounds, like psoralen, that can cause sleepiness or drowsiness.
- Enhanced Sedation: When combined with other central nervous system (CNS) depressants, including prescription sedatives like benzodiazepines (e.g., lorazepam) and hypnotics (e.g., zolpidem), celery can significantly increase drowsiness. This can affect cognitive function and motor skills more than the medication alone.
Comparison: Forms of Celery and Interaction Risk
| Feature | Fresh Celery (Food Amounts) | Celery Juice | Celery Seed Extract / Supplements |
|---|---|---|---|
| Concentration | Low | High | Very High |
| Vitamin K Content | Moderate, consistent amount for a typical serving. | Concentrated, can significantly alter daily intake. | Highly concentrated, poses highest risk for vitamin K-related interactions. |
| Diuretic Effect | Mild | Moderate | Strong |
| Effect on Blood Pressure | Mild, generally negligible for most individuals. | Potentially significant, especially with high intake. | Most potent, highest risk of additive blood pressure-lowering effect. |
| Photosensitization | Low risk for phytophotodermatitis, unless handling pink-rot-infected celery or exposed to tanning beds. | Increased risk with high consumption and UV exposure. | Increased risk of phototoxic reaction, especially with strong UV exposure. |
| Risk of Interaction | Low, generally safe. | Moderate to High, requires caution and consistency for those on interacting medication. | High, professional medical consultation is essential. |
Other Notable Interactions and Precautions
- Lithium: Celery can act as a diuretic, which may alter the body's excretion of lithium. This can increase lithium levels and lead to serious side effects. Medical supervision is essential for anyone taking lithium.
- Thyroid Medications: Celery seed has been shown to potentially interfere with thyroid function. It may reduce the effectiveness of thyroid medications like levothyroxine.
- Liver-Metabolized Drugs: Celery might alter the activity of certain liver enzymes, such as cytochrome P450, that are responsible for metabolizing many medications. This can affect the potency and side effects of drugs like venlafaxine (Effexor). Research in rats has shown celery extract can increase the bioavailability of captopril by inhibiting its metabolism.
- Surgery: Due to its potential to affect blood clotting and the central nervous system, it is recommended to stop taking medicinal amounts of celery at least two weeks before scheduled surgery.
Conclusion
While fresh, raw celery is a healthy food for most people, the concentrated forms found in juices, extracts, and supplements can pose significant risks for those on certain medications. The key to safe consumption is understanding the concentration and potential for interaction. The most common and serious concerns involve blood thinners, blood pressure medications, diuretics, and sedatives. It is vital to talk to a healthcare provider before making substantial changes to your celery intake, especially if you are on medication. By doing so, you can enjoy the benefits of celery while ensuring your medication remains safe and effective.
For more information on drug-herb interactions, the National Institutes of Health (NIH) provides extensive resources and research studies on the topic.
