Who Should Not Take Quercetin?

Disclaimer: Initially drafted by AI, this article was edited by a human author to ensure accuracy and quality.

Quercetin is an antioxidant and a type of molecule known as a flavonoid. Naturally found in plants, fruits, and vegetables, quercetin is best known for its ability to relieve joint health issues and the symptoms of allergies, asthma, and hay fever.

But while it has some benefits, it’s not for everyone. In fact, some people absolutely should not take quercetin. These include people with kidney or liver disease and those taking anti-coagulant medications such as warfarin. Pregnant women should also check with their doctor before taking quercetin or any supplement for that matter.

How Does Quercetin Work?

As I mentioned earlier, quercetin is a natural plant compound with antioxidant properties. Antioxidants in general help to protect your body from oxidative stress, but quercetin has some interesting, specific benefits. Quercetin works to prevent the oxidation of LDL cholesterol, which can cause atherosclerosis and heart disease. It also has anti-inflammatory effects in the body, which may help with pain and swelling caused by arthritis and other chronic inflammatory conditions. 

Quercetin for nasal congestion – yes, that’s what it’s used for too. Quercetin has been found to help treat the symptoms of allergies, colds, and the common flu. It is known to help relieve the severity of these illnesses by opening up airways that have become narrowed from swelling or irritation. As it turns out, quercetin is also suggested by some studies to combat prostate cancer. Such as this one.

Quercetin Supplements are Beneficial – But Not for Everyone

Quercetin has many benefits for our body, including improved memory, but too much of it can cause nausea and diarrhea (more on that in the “dosage” section). As with anything, you should take it in amounts that have been shown to be safe – up to 2,000mg per day, less is better, especially if taking it long-term. Don’t overdo it thinking it will lead to greater benefits (it won’t!). Also, we always recommend getting your nutrients from food if you can, and only supplement if you’re not able to eat a nutrient-rich diet all the time. The most common source of quercetin is from foods like red wine, green tea, grapefruit and onions.

Is Quercetin Safe?

Generally yes, while there are some people who shouldn’t take quercetin, for most of us it will be safe. Remember it’s naturally found in some foods? As a result, it’s a harmless compound for most individuals who’re healthy who take it in smaller amounts, let’s say 100-200mg per day. But, taking higher doses can in rare cases lead to dizziness, nausea, and diarrhea to name a few side effects.

The biggest risk population for quercetin is those who are on blood thinning medications. Quercetin can increase their effects, potentially increasing the risk of bleeding.

Quercetin Dosage – How Much is Too Much?

As mentioned, quercetin is safely tolerated in dosages lower than 1,000mg. This dosage has been safely used in studies for up to 12 weeks. Some experts like Examine.com suggest this dosage is a bit higher, up to 2000mg per day.

However, if you want to use quercetin for prolonged periods of time, it’s smart to stick to lower dosages such as 200-300mg of quercetin per day. It’s important to remember that we also get some quercetin from food, so additional supplementation may not always be necessary. Especially if you’re already eating plenty of quercetin-rich foods. You can take quercetin at any time of the day. If you want quercetin to kick in faster, try taking it on an empty stomach.

Who Should Not Take Quercetin With Bromelain?

The answer to who should avoid taking quercetin with bromelain is the same as the answer to who shouldn’t take quercetin. Bromelain doesn’t change the picture. People with bleeding disorders, those with kidney issues, and breastfeeding and pregnant women should all avoid taking quercetin with bromelain, unless otherwise told by their doctor.

Final Word

To recap, quercetin is a natural substance found in many fruits and vegetables. However, as beneficial as it is, some people are to steer away from quercetin:

  1. Pregnant and Breastfeeding Women: It’s best for pregnant or breastfeeding women to avoid quercetin supplements as the effects on the baby are not well-known. source
  2. People with Kidney Problems: Quercetin might make kidney issues worse. If someone has kidney problems, they should not take quercetin. source
  3. Individuals on Blood Thinners: Quercetin can enhance the effect of blood-thinning drugs, which might increase the risk of bleeding. source

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    1. Hi Molly,

      That’s something that you need to check with your doctor depending on your health status and any medications you take.

      With that said, everything you listed sounds OK and they can be combined together, yes.


      Keefe Memorial Staff

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