Hound's tongue
Hound's tongue


Hound's tongue (Cynoglossum officinale) is a plant. The leaf and root are sometimes used to make medicine.

Hound's tongue contains chemicals called pyrrolizidine alkaloids (PAs). These chemicals can be toxic to the lungs and the liver and should be avoided.

People use hound's tongue for infections, wound healing, and many other purposes, but there is no good scientific evidence to support any use. Hound's tongue can also be unsafe.
When taken by mouth: Hound's tongue is likely unsafe. It contains chemicals called pyrrolizidine alkaloids (PAs), which may block blood flow in the veins and cause liver damage. PAs might also cause cancer and birth defects. Do not use hound's tongue preparations that are not certified and labeled "PA-free".

When applied to the skin: It's likely unsafe to apply hound's tongue to broken skin. The dangerous chemicals in hound's tongue can be absorbed quickly through broken skin and can lead to serious side effects. There isn't enough information to know if it's safe to apply certified PA-free hound's tongue to the skin. It's best to avoid use.

Special Precautions & Warnings:

Pregnancy and breast-feeding: It's likely unsafe to use hound's tongue when pregnant or breast-feeding. It contains chemicals that can cause birth defects and liver damage. Stay on the safe side and avoid using any hound's tongue preparation when pregnant or breast-feeding.

Liver disease: Hound's tongue contains chemicals called pyrrolizidine alkaloids (PAs). These chemicals can cause liver damage and may make liver disease worse.


There is interest in using hound's tongue for a number of purposes, but there isn't enough reliable information to say whether it might be helpful.
Likely effective Effectiveness definitions
Possibly effective Effectiveness definitions
Likely ineffective Effectiveness definitions
Possibly ineffective Effectiveness definitions
Insufficient evidence Effectiveness definitions

Dosing & administration

There isn't enough reliable information to know what an appropriate dose of hound's tongue might be. 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 a healthcare professional before using.

Interactions with pharmaceuticals

Medications that increase break down of other medications by the liver (Cytochrome P450 3A4 (CYP3A4) inducers)

Interaction Rating=Moderate Be cautious with this combination.

Hound's tongue is changed and broken down by the liver. Some drugs increase how quickly the liver changes and breaks down hound's tongue. This could change the effects and side effects of hound's tongue.

Interactions with herbs & supplements

Herbs that increase the breakdown of other herbs by the liver: The body processes hound's tongue in the liver. Some supplements might increase how quickly it's changed by the liver. This might increase the toxic effects of hound's tongue.

Examples of supplements with this effect include echinacea, garlic, licorice, schisandra, and St. John's wort.
Pyrrolizidine alkaloids (PAs)-containing herbs and supplements: Hound's tongue contains PAs, dangerous chemicals that can harm the liver. Taking it along with other supplements that also contain these chemicals might increase the chance of developing serious side effects, including liver damage and cancer.

Examples of supplements containing PAs include alkanna, butterbur, coltsfoot, comfrey, and groundsel.

Interactions with foods

There are no known interactions with foods.
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This monograph was last reviewed on 16/11/2023 11:00:00 and last updated on 19/02/2022 08:27:11. Monographs are reviewed and/or updated multiple times per month and at least once per year.
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