Herbs

Angelica

Stimulates menstruation.
Source
Unsafe

Avocado Leaf

Toxic to many animals and can cause problems with lactation in animals. Studies are inconclusive on humans.
Source
Careful

Barberry (Berberis)

Can cause brain damage in newborns.
Source
Unsafe

Basil

Excessive quantities can cause a build up of toxic oils. In food is fine, but should not be consumed in concentrated or medicinal forms.

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Safe

Bay Leaf

Reportedly aids flow of breast milk but historically used as an abortifacient (substance to induce abortions) in large quantities.

Source
Careful

Bouquet Garni

This is a herb blend which contains a variety of other ingredients in small quantities. Most should be safe, but double check the ingredients.
Safe
Safe
Safe

Cicely

Always wash thoroughly.

Strong infusions have been traditionally used to induce labour.

Source
Safe

Clary Sage

Has been known to stimulate labour in oil form.
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Careful
Safe

Cuban Oregano

Like true oregano, this should not be consumed as a tea or oil.
Safe
Safe
Safe
Safe

Fines Herbes

This is a herb blend which contains a variety of other ingredients in small quantities. Most should be safe, but double check the ingredients.
Safe
Safe

Golpar (Hogweed)

Reported to have abortifacient qualities. The juice/sap from the plant is toxic and can cause third-degree burns in severe cases.
Unsafe

Herbes de Provence

This is a herb blend which contains a variety of other ingredients in small quantities. Most should be safe, but double check the ingredients.
Safe

Holy Basil (Tulsi)

Linked to fertility issues and can cause the uterus to contract.
Source
Unsafe

Hyssop

Okay in food, unsafe as a tea. Large quantities can reportedly cause miscarriage.
Source
Careful
Safe

Italian Seasoning (Mixed Herbs)

This is a herb blend which contains a variety of other ingredients in small quantities. Most should be perfectly fine, but double check each one if you're worried.
Safe

Jasmine

Unsafe as a tea or oil as may cause contractions.
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Careful

Juniper

Juniper can stimulate menstruation.
Source
Unsafe
Safe

Lavender

Unsafe in first trimester and totally unsafe if you have a history of miscarriage. Oil and tea forms otherwise safe.
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Careful
Source
Safe
Source
Safe
Safe

Lemongrass

Safe in food, unsafe in medicinal or concentrated forms.

Source
Careful
Source
Unsafe

Long Coriander (Culantro)

Always wash thoroughly.

Source
Safe

Lovage

Can cause fluid volume issues due to water retentive properties.
Source
Unsafe

Marjoram

High quantities can reportedly cause womb contractions, miscarriage, or premature labour.
Source
Safe

Mastic

As a gum, mastic is used widely in Mediterranean dishes and desserts (including Turkish Delight). It is also used as a chewing gum. Avoid the leaf, especially in the first trimester.
Source
Careful

Mexican Oregano

Like true oregano, this should not be consumed as a tea or oil.
Safe

Mint

All forms of mint are safe in reasonable amounts.
Safe

Mugwort

Can bring on menstruation and has been historically used to induce abortions.
Source
Unsafe

Oregano

The oil or tea form of oregano are considered uterine stimulants.
Source
Safe

Parsley

High doses of parsley can stimulate the uterus and even cause miscarriage.
Source
Safe

Peppermint

Safe as a tea. It can worsen heartburn, especially in later stages of pregnancy, so be aware if it is a particular issue for you.
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Safe

Rosemary

Has diuretic properties in high doses. Some people believe it has emmenagogue properties as well.
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Safe

Rue

Rue is toxic in large quantities, and can cause burn-like blisters. In remedies and herbal supplements it can cause stomach and kidney issues.
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Unsafe

Safflower

The seed oil is considered safe (consult with your doctor first), but the flower itself is toxic.
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Careful

Sage

Concentrated doses (such as a tea or oil) can lead to abdominal pain.
Source
Safe
Source
Safe
Safe
Safe
Safe

Thyme

Wild Thyme is also safe.
Safe
Safe

Vietnamese Coriander

Has many names, including hot mint, finger mint, Vietnamese cilantro, rau ram, and laksa leaf.
Unsafe
Safe

Wintergreen

Can lead to kidney issues in high doses.
Source
Careful

Wormwood

May stimulate the womb, cause miscarriage, premature labour, fits, and kidney failure.
Source
Unsafe

Yarrow

Can stimulate menstruation.
Source
Unsafe

Zedoary

Can cause miscarriage.
Source
Unsafe