Safe Use Guidelines for 90 Herbs

Yes, there really are 90 common herbs covered below. They are listed alphabetically so just scroll down to find those of interest.

The guidelines identify contraindications for use such as existing medical conditions, existing use of certain pharmaceuticals, pregnancy, childhood and so on. Remember that herbs have been used for centuries so don't be put-off by what you may find. Just follow the safe use guidelines to enjoy the benefits of herbal medicine.

Guide to the Safe Use of Herbs
Herb Safety Guidelines
Agrimony
  • Do not take if constipated.
Aloe Vera
  • Aloe stimulates uterine contractions. It should be avoided during pregnancy. As aloe is excreted in the breast milk is best avoided during breast feeding as it may act as a purgative on the baby.
  • Avoid if you have kidney disease or hemorrhoids.
  • Do not apply the gel to any surgical incision as it may delay the healing.
  • Do not ingest the dried leaf gel as it is a habit forming laxative. Taken in large amounts or for long periods, they may be harmful to the kidneys and gastrointestinal tract.
  • Avoid taking aloe products with cardiac medications, such as antiarrhythmics. A possible interaction may occur, due to potential potassium loss induced by aloe preparations.
  • Do not confuse aloe vera with bitter aloes or other aloe species as some are poisonous.
Angelica
  • Use sparingly and only for short periods of time.
  • It increases the sensitivity to the sun.
Arnica
  • This herb should not be taken internally as it has a highly toxic effect. It should only be used on unbroken skin and you should stop using it if there are any signs of dermatitis.
  • The homeopathic preparation of the herb is safe to use internally, because of the low dosages.
  • Do not use arnica products for a prolonged period of time.
Ashwagandha
  • Do not use in combination with barbiturates as it may intensify their effect.
  • Do not use in pregnancy.
Birch bark
  • Do not use if you need to avoid aspirin.
Black Cohosh
  • Do not use in pregnancy, particularly the early stages.
  • It is best used under the supervision of a herbal practitioner.
  • Avoid black cohosh if you have an estrogen receptor Ė positive (ER+) tumor.
  • Continuous treatments should be limited to a maximum of 6 months.
  • If you have high blood pressure, kidney or liver ailments you should consult with a health professional before taking this herb.
  • Occasional gastrointestinal discomfort has been reported as a possible side effect.
  • High doses may cause dizziness, impaired vision, vomiting and circulatory problems.
Blessed Thistle
  • Do not use this herb internally during pregnancy.
  • Strong infusions may cause vomiting and diarrhea.
Boneset
  • May cause adverse reaction in those with allergies or sensitivities, especially to chamomile, feverfew, ragweed or members of the daisy family.
  • Can cause vomiting and diarrhea in large doses.
Blue Cohosh
  • Do not use blue cohosh in the early stages of pregnancy. It is best used when labour has commenced.
Calendula
  • Calendula should not be used internally during pregnancy.
  • Do not confuse this plant with the French or African marigolds (Tagetes sp.).
California poppy
  • Do not use in combination with antidepressant MAO inhibitors such as pheneizine sulphate unless under the supervision of a health professional.
  • Do not use during pregnancy
Cascara sagrada
  • Do not use during pregnancy.
  • Do not use if you have any digestive tract inflammation, obstruction or pain.
  • Discontinue treatment after 14 days as it can cause laxative dependency and diarrhea.
Castor
  • Do not use during pregnancy.
  • Do not use internally if you have any intestinal blockage or pain.
  • Discontinue treatment after 10 days.
Cat's claw
  • Do not use if you have hemophilia.
  • Side effects include headaches, stomach ache and difficulty breathing.
Cayenne Pepper
  • Avoid cayenne if you are prone to overheating or acidity of the stomach.
  • Always handle the peppers with care. Wear gloves or at least wash your hands carefully after preparation.
  • Never touch your eyes or any other sensitive part. Don't touch children or place on broken skin.
Celery
  • Small amounts used in cooking are generally safe but do not take internally in medicinal doses during pregnancy or if you have a kidney disorder.
Chamomile
  • Chamomile is included in the Generally Regarded As Safe (GRAS) list by the FDA.
  • Do not ingest large amounts of chamomile tea during pregnancy, since some of the plantís ingredients may cause uterine contractions.
  • If you are allergic to other plants belonging to the Daisy family, such as ragweed, elecampane and arnica you may also be sensitivity to chamomile. If you have asthma†take chamomile infusions with caution, especially if you are allergic to these plants.
  • Chamomile may cause allergies either by direct contact with the plant, employing it as an eye wash, skin cream or drinking the tea.
  • Chamomile may interfere with blood clotting, do not use together with aspirin, warfarin or other substances that possess anticoagulant (blood-thinning) action.
  • Do not take chamomile with diazepam or other sedative medications, since this may increase the potency of the drugs.
Chasteberry
  • Chasteberry may counteract the effectiveness of the birth control pill.
  • Can elevate blood pressure. You will need to read the product labels carefully if you have high blood pressure and should consult your health professional before using.
Cinnamon
  • Avoid cinnamon in large doses during pregnancy or lactation, only use as a spice or food condiment.
  • Avoid infusions in large amounts if you have an ulcer, as cinnamon can be irritating to the stomach lining.
  • Contact dermatitis, in susceptible individuals, has been reported after using ointments cinnamon containing.
  • Undiluted essential oil should not be applied directly to the body.
Cleavers
  • Cleavers should not be used by diabetics or anyone with a tendency towards diabetes.
Cloves
  • Do not use the essential oil during pregnancy.
  • Do not use the essential oil on sensitive skin.
Comfrey
  • The presence of liver toxic substances in comfrey have raised doubts over the safety of the herb when taken internally. These are likely to prove ill-founded but it is better to be on the safe side and avoid taking the root internally and avoiding excessive use of the leaves internally.
  • Do not use on open, unclean wound or very deep wounds as fast healing can mean that dirt and bacteria are trapped inside.
Coltsfoot
  • The presence of pyrrolizidine alkaloids has raised worries about possible liver damage. However, there is no evidence that taking coltsfoot medicinally is harmful. Nevertheless avoid taking large amounts if you are pregnant or breastfeeding.
Dandelion
  • If children excessively suck the milky juice it may lead to nausea, vomiting or diarrhea.
  • If you have gallbladder disease consult your health professional before taking dandelion root preparations.
  • Do not use dandelion as a weight loss aid.
Devil's Claw
  • If you have gallstones consult your health professional before taking.
  • Do not use if you have gastric or duodenal ulcers.
Dill
  • Dill seeds contain high levels of sodium and should not be taken by anyone on a low sodium diet.
  • Should be avoided by anyone who is allergic or sensitive to spices as it could cause an adverse reaction.
Echinacea
  • Large doses may cause nausea and dizziness.
  • Do not take continuously for more that three months.
  • Do not take if you have an auto-immune disorder such as lupus or multiple sclerosis as echinacea stimulates the immune system.
  • Do not take if you have tuberculosis.
  • Echinacea can cause an allergic reaction in a small percentage of people.
Elder
  • The leaves and the bark of the elder are poisonous and should only be used as directed. Do not take them internally.
Elecampane
  • Small amounts used in cooking are generally safe but do not use internally in medicinal doses during pregnancy.
Ephedra
  • Do not take more that 8 milligrams in a single dose.
  • Avoid ephedra products that contain caffeine. Avoid foods that contain caffeine while using ephedra.
  • Avoid ephedra if you have high blood pressure, heart problems, diabetes, prostate problems, glaucoma, thyroid disease or are taking medication for asthma.
  • Do not take the herb for longer than 7 days and only take the herb under the supervision of a health professional.
  • Do not take during pregnancy.
Eucalyptus
  • Large amounts of an infusion can cause nausea and vomiting.
  • Don't use eucalyptus oil on the skin of babies or young children.
False Unicorn Root
  • Large doses may cause nausea and vomiting.
Fennel
  • Small amounts used in cooking are generally safe but do not take internally in medicinal doses during pregnancy.
Fenugreek
  • Small amounts used in cooking are generally safe but do not take internally in medicinal doses during pregnancy.
Feverfew
  • Avoid taking feverfew during pregnancy.
  • Fresh leaves may cause mouth ulcers in sensitive people.
  • Do not take if you are already taking blood thinning drugs such as warfarin.
Flaxseed
  • Do not use if you have a bowel obstruction.
  • Take with at least 8 ounces of water.
Garlic
  • Garlic is an anticoagulant so don't mix too much garlic with vitamin E or aspirin or other herbs that may have an anticoagulant effect such as, catís claw, ginger, ginkgo, ginseng or feverfew.
  • Use with caution if you have diabetes (garlic may lower blood glucose levels).
  • Do not use in large amounts if you have a thyroid dysfunction, as garlic may interfere with iodine metabolism.
  • Do not ingest in large quantities during pregnancy and lactation as large amounts may induce labour. The small amounts used in cooking are generally safe.
  • Do not use in medicinal doses for children under ten years of age without consulting your health professional.
Gentain
  • May cause nausea and vomiting if taken in large doses.
  • Do not use if you have high blood pressure, gastric or duodenal ulcers or gastric irritation or inflammation.
Ginger
  • It is not recommended for those who do not tolerate heat well or for people with gastritis or peptic ulcers. Small amounts used in cooking are generally safe.
  • Do not use in large doses if you have gallstones, as gingerís effects may stimulate the gall bladder, worsening symptoms and causing unnecessary pain.
  • Gingerís components may interfere with normal blood clotting. As a precaution, suspend the use of this herb at least one week before surgery. Do not use with other plants or herbal products that may interfere with normal blood clotting, such as garlic, ginseng or ginkgo. Do not use with drugs that interfere with blood clotting, such as aspirin, heparin or warfarin (coumadin).
  • Try not to take too often or in too strong a dose while pregnant.
  • Very high doses may cause a reduction of blood sugar levels.
Ginkgo Biloba
  • Ginkgo may be toxic in large amounts and can interact with other drugs, such as warfarin and aspirin.
  • As a general rule it is best to consult your health professional before taking this herb.
Ginseng
  • Ginseng should be taken according to the directions and should be take three weeks out of four for the best effect.
  • Avoid caffeine and other stimulants when taking ginseng.
  • Occasionally, the use of this herb can cause headaches.
  • Avoid large doses or prolonged treatments if you have high blood pressure. Check with your health professional before taking this herb.
  • Do not give products containing ginseng to small children.
  • Ginseng may lower blood sugar levels and thus interact with oral anti-diabetic medications, increasing their effects. Monitor your blood sugar levels closely.
  • Ginseng may interfere with normal blood clotting. Avoid combining this plant with medications that thin the blood, such as aspirin or warfarin. If you are scheduled for surgery, suspend the use of this herb or supplements containing it, at least one week prior to the operation.
  • Do not use continually for more than 3 months, unless under the supervision of a health professional.
  • Avoid taking ginseng at night if you suffer from any sleeping disorder, such as insomnia.
Golden Seal
  • Avoid during pregnancy because of its effect on the involuntary muscle of the uterus.
Guarana
  • Contains twice as much caffeine as coffee and can over stimulate the nervous system when used in excessive amounts for a long period of time.
  • Can irritate the gastrointestinal wall.
Gurmar
  • If you have diabetes do not use without the supervision of a health professional as it may effect your blood sugar levels.
Hawthorn
  • If you have a cardiovascular condition do not take for more than a few weeks without the supervision of a health professional. Other medication dosages may need to be reduced.
Hops
  • Do not use in cases of marked depression.
  • The pollen from the hops may cause contact dermatitis.
  • Use only fresh hops or dried hops that are less than 12 months old.
Horse chestnut
  • May interfere with the action of other drugs, especially blood thinners such as warfarin.
  • May irritate the gastrointestinal tract.
Horseradish
  • Do not use horseradish to excess as it can cause gastric irritation.
  • Horseradish can depress the thyroid gland function so do not take it if your thyroid hormone levels are low.
Horsetail
  • Do not use the tincture if you have heart or kidney problems.
  • May cause a deficiency of thiamine, Vitamin B1.
Hyssop
  • Be careful of strong infusions or infused oils as strong doses may trigger fits.
  • Do not use in pregnancy.
Juniper Berries
  • Due to the actions on the kidneys, juniper berries should be avoided in any cases of kidney disease.
  • It should be avoided in pregnancy.
  • The very young and the very elderly would be considered 'at risk' users and therefore it is not recommended for them.
Kaffir potato
  • May intensify the effects of asthma or high blood pressure medications. Do not use without the supervision of a health professional.
Kava
  • Do not use in combination with alcohol or barbiturates.
  • Do not take more than the recommended dose.
  • Exercise caution when driving or operating machines as it has a muscle relaxant action.
Kelp
  • Use no more than once per day if you have high blood pressure or heart problems.
  • Do not use if you have hyperthyroidism.
  • Long term use of kelp is not recommended.
Lady's Mantle
  • Avoid taking during pregnancy.
  • Lady's mantle contains tannins, so do not take for long periods without a break.
  • If it is used regularly it may cause constipation.
Lavender
  • Small amounts used in cooking are generally safe, but do not take internally in medicinal doses during pregnancy.
Lemon Balm
  • Do not use lemon balm if you have an underactive thyroid.
Licorice
  • If you take licorice in large doses for a year or so you can develop a hormonal problem called pseudoaldosteronism. This is rare but it could account for the number of reported side affects that are associated with licorice use. These side effects include high blood pressure. It is therefore recommended that you not take it for longer than 6 weeks. This should mean that the side effects are unlikely to occur.
  • Its use in hypertension (high blood pressure) or with digitalis should be discouraged.
  • Do not take licorice during pregnancy.
Lobelia
  • Although the toxicity of this herb has not been established, the presence of the nicotine-like alkaloid, lobeline, has led to its control under the 1968 Medicines Act in the UK. It is not permitted to be sold to the general public.
  • Do not use during pregnancy.
Marjoram wild
  • This herb has a stimulating effect on the uterus. Small amounts used in cooking are generally safe, but do not take internally in medicinal doses during pregnancy.
Marshmallow
  • If it is taken in combination with medications it may slow their absorption. They need to be taken separately.
Meadowsweet
  • Do not take if you are allergic to aspirin.
  • Do not take over a long period of time if you are have a tendency to constipation.
Motherwort
  • Some people get a skin rash after handling motherwort.
Mugwort
  • Do not take in pregnancy or when breastfeeding.
  • Do not take for long periods of time without the supervision of a health professional.
Mustard
  • Mustard acts by irritating the skin and therefore increases the blood supply to the area. Do not apply to the skin for too long or too often as blistering may occur. If an irritation does occur rub the area with olive oil.
  • Large internal doses may irritate the intestinal linings.
  • Long term internal use may also damage the kidneys and prostate.
Myrrh
  • Avoid using myrrh during pregnancy and only use when childbirth is imminent.
  • Do not use if you have any type of uterine bleeding.
  • Can cause diarrhea and irritate the kidneys.
Oak Bark
  • Do not use if you have extensive skin damage.
Parsley
  • Small amounts used in cooking are generally safe but do not take the seeds in medicinal doses during pregnancy.
Pasque Flower
  • Never use this plant fresh as it is poisonous.
  • Do not store the dried herb for more than one year.
Pennyroyal
  • Avoid during pregnancy.
Peppermint
  • Avoid using peppermint oil with babies.
Poke Root
  • Never use poke root in pregnancy.
  • Only use the poke root dried and in small doses. In large doses it will cause vomiting and diarrhea.
  • Poke root may be toxic if taken in large doses or for an extended period of time. It would be best not to take this herb unless under the supervision of a health professional.
Psyllium seed
  • Do not use if you have a bowel obstruction.
  • Take with at least 8 ounces of water 1 hour after taking other medication.
Rhubarb
  • Do not use if you have an internal obstruction, abdominal pain of unknown origin, or inflammation of the digestive tract.
  • Use caution if you have a history of kidney disease.
  • Stop treatment after 10 days.
Rosemary
  • In therapeutic amount it may cause excessive menstrual bleeding. It is considered safe when it is used as a spice.
Sage
  • Do not use sage when pregnant or while breast feeding. Small amounts used in cooking are generally safe.
  • Do not take medicinal doses internally if you are an epileptic.
  • In therapeutic amounts it can increase the sedative effects of medications.
  • Do not take if you are hypoglycemic.
  • It is considered safe when it is used as a spice.
Sassafras
  • The constituent of the volatile oil, safrole, is both neurotoxic and hepatotoxic in large doses. This is very unlikely to be a problem in normal therapeutic doses. Take only for a limited period of time.
Saw Palmetto
  • Before using this herb to treat an enlarged prostate consult your health professional for diagnosis and monitoring.
St John's Wort
  • This herb can cause sensitivity to sunlight.
  • When taken internally this herb can cause stomach upset, dizziness and fatigue.
  • St John's wort reacts with some medications (including warfarin, immuno-suppressant drugs, some HIV and anti-epileptic medications and other antidepressants). So always check with your health professional before taking this herb.
  • It increases the production of liver enzymes that break down medications. This means that it can decrease the effectiveness of some medications, including the contraceptive pill.
  • It is not recommended that it be used in cases of marked depression.
  • If using the herb for its mood-elevating effects you need to be patient as it takes 4 to 6 weeks to take effect.
Senna
  • Do not use if you have a bowel obstruction.
  • Take with at least 8 ounces of water 1 hour after taking other medication.
Sorrel
  • If you have a history of kidney stones do not use without the supervision of a health professional. It contains oxalates and tannins that may adversely affect this condition.
Tansy
  • Avoid during pregnancy.
  • It should not be used for a long period of time or in high doses.
  • It is not recommended that it be used without the supervision of a health professional.
  • It can be irritating and narcotic.
Thyme
  • Small amounts used in cooking are generally safe but do not take internally in medicinal doses during pregnancy or if you have liver or kidney disease.
Turmeric
  • Do not use as in medicinal doses if you have excessive stomach acid, ulcers, gallstones or bile duct obstruction.
Valerian
  • Do not take valerian if you are already using sleeping tablets.
  • Do not take over a long period of time (more that 2-3 weeks) without a break.
  • Do not confuse this plant with false valerian, also known as kiss me quick (Centranthus ruber.)
  • Valerian is not related to the pharmaceutical drug valium.
  • It may cause heart palpitations and nervousness in those who are sensitive to it. If such stimulation occurs discontinue its use.
Willow
  • Do not use if you are allergic to aspirin.
Witch Hazel
  • Be cautious with the ingestion of large doses of witch hazel as the astringent tannins can cause abdominal distress and possibly liver damage.
Wormwood
  • Avoid taking wormwood during pregnancy.
  • There are many species that are known as wormwood. Positive identification of the correct species of wormwood is often difficult. Erroneous identification of a plant could result in negative effects of the plant upon the user.
  • Avoid use in small children, especially those less than 6 years of age.
  • Do not use wormwood if you are taking medication for seizures.
  • Avoid† taking wormwood if you suffer from nervous disorders.
  • Do not take if you have cirrhosis, hepatitis, gall bladder obstruction or kidney disease.
  • If you have a stomach or intestinal ulcers you should avoid this herb, due to its potentially irritating action.
  • Treatment with wormwood infusion should not be prolonged for more than a few days.
Yarrow
  • Avoid the use of yarrow in pregnancy.
  • It can cause a severe hypersensitivity reaction in a small number of people. Be very cautious the first time that you use it and never use it if you are allergic to other plants in the Asteraceae family to which the yarrow belong.
  • Do not take internally if you are taking blood thinning drugs.
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References

Duke, J. A. 2000, Anti-aging Prescriptions. Rodale.

Hoffmann, D. 2000, The New Holistic Herbal. Element Pub.

McIntyre, A. 1995, The Complete Women's Herbal. Henry Holt Reference Books

Shaw, N. 2002, Herbalism. Element

Woodward, P. 2003, Grow Your Own Herbal Remedies. Hyland House.

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