Sweet vernal grass
Sweet vernal grass


Sweet vernal grass is a plant. The whole plant is used to make medicine.

People use sweet vernal grass pollen combined with other grass pollens in a tablet placed under the tongue. This tablet is FDA-approved for the treatment of hay fever in people with grass pollen allergies.

Despite serious safety concerns, people take dried sweet vernal grass by mouth for headache, nausea, sleeplessness, and conditions of the urinary tract, but there is no good scientific evidence to support these uses.

In foods, sweet vernal grass is used as a flavoring agent, including in Russian brandies.
When taken by mouth: A specific, FDA-approved prescription product (Oralair) is LIKELY SAFE when placed under the tongue as prescribed. This product contains a mixture of sweet vernal grass pollen with other grass pollens.

However, dried sweet vernal grass is LIKELY UNSAFE when taken in large quantities. It contains a chemical that can slow blood clotting. In addition, sweet vernal grass can cause dizziness, headaches, and liver problems.

When applied to the skin: There isn't enough reliable information to know if sweet vernal grass is safe or what the side effects might be.

Special Precautions & Warnings:

Pregnancy and breast-feeding: It's POSSIBLY SAFE to place a specific FDA-approved prescription medication under the tongue while pregnant. This product contains a mixture of sweet vernal grass pollen and other grass pollens. It's LIKELY UNSAFE to take dried sweet vernal grass by mouth if you are pregnant or breast-feeding. It contains a chemical that might slow blood clotting.

Surgery: Dried sweet vernal grass taken by mouth might slow blood clotting. There is concern that it might cause extra bleeding during and after surgery. Stop using dried sweet vernal grass at least 2 weeks before a scheduled surgery.


NatMed Pro rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
Likely effective Effectiveness definitions
  • Hay fever. An FDA-approved prescription product (Oralair) containing sweet vernal grass, orchard grass, perennial rye grass, Timothy grass, and Kentucky blue grass pollen extracts can reduce allergy symptoms in people with grass pollen allergies.
Possibly effective Effectiveness definitions
Likely ineffective Effectiveness definitions
Possibly ineffective Effectiveness definitions
Insufficient evidence Effectiveness definitions
  • Headache.
  • Nausea.
  • Sleeplessness.
  • Urinary tract problems.
  • Other conditions.
More evidence is needed to rate the effectiveness of sweet vernal grass for these uses.

Dosing & administration

The appropriate dose of sweet vernal grass depends on several factors such as the user's age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for sweet vernal grass. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.

Interactions with pharmaceuticals

Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)

Interaction Rating=Moderate Be cautious with this combination.

Dried sweet vernal grass taken by mouth can slow blood clotting. Taking dried sweet vernal grass along with medications that also slow clotting can increase the chances of bruising and bleeding.

Some medications that slow blood clotting include aspirin, clopidogrel (Plavix), diclofenac (Voltaren, Cataflam, others), ibuprofen (Advil, Motrin, others), naproxen (Anaprox, Naprosyn, others), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, warfarin (Coumadin), and others.

Interactions with herbs & supplements

Herbs and supplements that might slow blood clotting: Dried sweet vernal grass taken by mouth might slow blood clotting. Taking it along with other herbs that also slow clotting can increase the chances of bruising and bleeding. Some herbs that can slow blood clotting include angelica, clove, danshen, garlic, ginger, ginkgo, Panax ginseng, horse chestnut, red clover, turmeric, and others. Don't take sweet vernal grass with any of these.

Interactions with foods

There are no known interactions with foods.


Sweet vernal grass contains ingredients that can thin the blood.
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This monograph was last reviewed on 20/04/2022 19:00:36. Monographs are reviewed and/or updated multiple times per month and at least once per year.
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