Is Quercetin Safe?
Many people want to know more about the safety of quercetin. For example, some people may be at a higher risk for developing problems while taking this supplement, so it is important to talk to your healthcare provider before using quercetin if you have kidney disease, any chronic or severe medical condition, or any allergies. Quercetin should never be given to newborns, as it may increase the risk of brain damage due to severe jaundice.
For many adults, short-term use of quercetin seems to be fairly safe when used in moderation. Some people may be more likely to experience problems due to quercetin. Therefore, you should talk with your healthcare provider prior to taking quercetin medicinally if you have:
- Kidney disease, such as kidney failure (known medically as renal failure)
- Any chronic or severe medical condition
- Any allergies, including allergies to foods, dyes, or preservatives.
Also, let your healthcare provider know if you are:
- Pregnant or thinking of becoming pregnant
You should also be sure to tell your healthcare provider about all other medicines you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
Warnings and precautions to be aware of concerning the safety of quercetin include the following:
- It is possible that taking quercetin intravenously (by IV) may cause kidney problems. This problem has not been reported with the oral form of the supplement.
- At this time, it is unknown if quercetin supplementation is safe for pregnant or breastfeeding women (see Quercetin and Pregnancy and Quercetin and Breastfeeding).
- Quercetin should never be given to newborns, as it may increase the risk of kernicterus (brain damage due to severe jaundice).
- Although short-term use of quercetin at reasonable dosages seems to be safe for most adults, it is not clear if long-term use (or use at high dosages) is also safe. Of course, a normal dietary intake of quercetin through a healthy and well-balanced diet is considered to be safe.
- Quercetin may theoretically interact with some medications (see Quercetin Drug Interactions).
- As a dietary supplement, quercetin is not as closely regulated as prescription (or non-prescription) drugs. It can be marketed without any proof that it is either safe or effective. Do not assume that just because a product is sold or advertised in the United States that it is safe or effective. Be sure to look for quercetin products from a reputable manufacturer. Your pharmacist is a good resource for information about which manufacturers are most reputable. This is especially important due to the toxic alkaloids found in some quercetin products.
- If you have a chronic or severe medical condition, it is always a good idea to check with your healthcare provider before taking any medication or supplement, including quercetin.