Short answer

We found no documented interaction between Herbal sleep blend and Quercetin in the sources below. That isn't proof the combination is right for you: check each one's cautions, and ask your pharmacist if you take medication.

Herbal sleep blend

What it is: A blend of calming herbs: valerian, hops, passionflower, skullcap and poppy.

What the research says: Evidence for valerian is inconsistent, and sleep doctors advise against it for chronic insomnia. Small studies suggest passionflower may add sleep time, and hops with valerian may help mild insomnia.

Cautions

• Valerian is generally safe short term; it can cause headache, stomach upset or vivid dreams, and withdrawal if stopped suddenly after long use.
• Passionflower can cause drowsiness or dizziness and shouldn't be used in pregnancy.
• Don't combine with alcohol.

Medicines to check

• Sedatives and sleep medicines: don't combine
• Anesthesia: stop at least 2 weeks before surgery (passionflower)
• Hormone-sensitive cancer: check with your doctor (hops)

In Holitro: Herbal Sleep Blend (450 mg per capsule)

Sources: NIH National Center for Complementary and Integrative Health: Valerian: Usefulness and Safety (updated May 2025); NIH National Center for Complementary and Integrative Health: Passionflower: Usefulness and Safety (updated April 2025); Memorial Sloan Kettering Cancer Center, About Herbs: Hops (updated February 2021)

Quercetin

What it is: A plant compound found in apples, onions and tea; the most common flavonoid in the diet.

What the research says: It hasn't been shown to treat any disease. Its anti-inflammatory effects come from lab studies; in athletes, any performance benefits were small.

Cautions

• No side effects were seen in athletes taking about 1,000 mg a day, but it hasn't been studied enough to know it's safe.

Medicines to check

• Some prescription drugs processed by the liver: it may increase their side effects (lab data)
• Losartan (a blood-pressure drug) and tamoxifen: animal or lab data only

In Holitro: Quercetin (500 mg per capsule)

Sources: Memorial Sloan Kettering Cancer Center, About Herbs: Quercetin (updated October 2023); NIH Office of Dietary Supplements: Dietary Supplements for Exercise and Athletic Performance (updated March 2021)

Check with your doctor or pharmacist, especially if you take medication.

Check your stack — free

Educational information only, not medical advice. This reflects general ingredient overlap, not a personalized safety review. Always check with your doctor or pharmacist before combining supplements, especially if you take medication, are pregnant or nursing, or manage a health condition. These statements have not been evaluated by the FDA.