Natural medicine has been in existence as long as man has walked the earth. There is a close relationship between spiritual, emotional, and physical that is interplayed with the environment that contribute to the overall well being of a person. To view a disease as only a set of symptoms to be blocked by the action of a drug, limits our ability to understand the nature of disease.
In a world where medicine has become more specialised, we often fail to take into account the whole individual and not just the diseased part of the person. Complementary medicine considers nutrient status, structural integrity, functional enzymatic activity, detoxification pathways and biochemical messengers to create the whole symptom picture.
There is a need to support organ structure and function and depleting nutrient status can make an individual more susceptible to illness. Use of natural remedies can strengthen health and vitality, improve quality of life and reduce life limiting symptoms.
People are looking for safer options than modern drugs to reduce potential risks and side effects; they are also seeking information on guidance in the use of natural remedies.Herbal remedies are widely used, estimates that a quarter of the people who use vitamins or herbal medicines do so, together with prescription medicines As a result many patients are at risk of having a herb–drug interaction.
Estimates are that approximately 50% of patients fail to mention use of herbal remedies to their health care professional, resulting in increased harm to patients. It is up to the health care professional to continue to educate the public about herb – drug interactions, in order to guard patients from choosing inappropriate and unsafe herbal medicines in relation to their current medical conditions and prescription medicines.
There are many ways to consider the usefulness of natural remedies and how they can be put into practice. Consider antibiotic resistant bacteria; could that be reduced if we used natural agents that improve immune competence more as a first line agent or a preventative?
Natural remedies can also be used alongside modern drugs, for example. In diabetics using a herb to improve the microcirculation to the eyes and thus reduce the risk of diabetic retinopathy. It would not be a cure for the disease, but it would help reduce the risks associated with the disease.
In China it is common for herbs to be combined with drugs. Their combination is sometimes incidental, but is often intentional and based on a prevalent favourable theory about using herbs and drugs. The general sense of the situation among Chinese doctors has been that herbs reduce the side effects of drugs and help them to perform their function better; in turn, drugs will make an herb formula work more strongly and quickly. Together, herbs and drugs may produce a more desirable result than either taken alone. NB it is not uncommon for Chinese medicine remedies to contain prescription medicines, such as steroids, anti–inflammatory, hormones etc&hellep;in ‘natural remedies’.
As an outcome of working within this scenario, little attention has been paid to adverse herb–drug interactions. We need to asses the strength of a natural remedy and the recommended dosage of the herbal preparation. i.e. a multiple ingredient supplement containing a small amount of interacting plant material is less likely to cause an interaction than a high strength standardised product.
It is not possible for the pharmacist to give an absolute assurance to a patient that the herbal product they wish to take will not interact with at modern drug regime, but we can give a good indication based on the information we have. Methods we can use to minimise or avoid the consequences of a potential interaction!
- Not taking the herb and drug at the same time
- Monitoring for potential side effects
- Monitoring for potential interactions
- Discussing with your pharmacist / Dr
Drugs can interact in two ways:
Alterations of absorption i.e. slippery elm – reduces absorption of thyroxine (helps to regulate metabolism) & lithium (a mood stabiliser):
- Changes in the gastrointestinal pH (i.e. changing the stomachs acid environment which can affect how much of a medicine is absorbed).
- Adsorption, chelation and other complex‘s (i.e. two products combining and affecting the solubility or absorption). Charcoal – is used for overdoses by this process to adsorb drugs.
- Changes in Gastro intestinal motility (how quickly a drug passes through the system).
- Protein binding – This can affect how much of a drug is available for absorption. Horse chestnut binds with plasma and tissue proteins and competes against warfarin, a medicine used to prevent blood clots.
- Changes in metabolism and elimination resulting in either increasing or decreasing the amount of drug available to have an effect:
- The interaction may involve a herb causing either an increase or decrease in the amount of drug in the blood stream.
- A decrease in the amount of drug could occur by herb components binding the drug and preventing it from getting into the blood stream from the gastrointestinal tract.
- A decrease in a drug could be by stimulating the production and activity of enzymes that degrade the drug and prepare it for elimination from the body.
- A decrease in drug dosage by virtue of an interaction could make the drug ineffective.
- An increase in drug dosage could make it reach levels that produce side effects.
Alterations in the way a drug affects a tissue or organ system. These interactions result in either enhancing or antagonising effects.
Change in first pass metabolism (the way the liver processes a drug) e.g. St John‘s Wort acts as an inducer of the liver enzyme system. This is responsible for the metabolism of a large number of drugs, therefore may see an accelerated metabolism and reduced plasma concentrations of various drugs.
When stopping St John‘s Wort it can take a few weeks for the enzymes to come back to normal.
Grapefruit juice – inhibits a transport protein that acts as a pump to move drugs across the cell wall, which can lead to higher levels of many drugs.
Ingestion of grapefruit juice and certain prescription drugs can significantly increase the availability of a drug in the body. This can lead to excessive beneficial effects (i.e. with medicines for lowering blood pressure, it could lower blood pressure too much and cause dizziness and blackouts) or cause an increase in side effects.
The effect is long lasting, so you need to avoid grapefruit juice altogether whilst on those medicines that are affected (rather than consuming grapefruit at a different time of day).
The pharmacist will put a warning on the prescription label for those affected, but they can include, some medicines for blood pressure, those to lower cholesterol, the oral contraceptive, some sleeping tablets even Viagra! If unsure about your medicines check with the pharmacist.
Note: While grapefruit juice has the reputation for interactions, the fruit may have the same effect if consumed in large amounts.
Other factors affecting interactions are age, genetics, ethnicity, liver and/or renal impairment, cigarette smokers.
Narrow therapeutic margin (the range of doses for a drug that will produce beneficial results without side effects is small) – digoxin, theophylline, warfarin, lithium.
Medicines with a narrow therapeutic margin are often used for life threatening conditions and therefore it could be quite dangerous for patients to commence a herbal remedy that will upset the fine balance of the drug.
- Digoxin (controls heart rate), some preparations with laxative effect (aloe, liquorice) decrease potassium and increase digoxin toxicity.
- Theophylline (eases breathing), any preparation that has stimulant effects i.e. caffeine (including guarana) may have additive central nervous system effects and increase theophylline levels.
- Herbal products with a diuretic effect(including caffeine products) a problem for patients on lithium which helps to stabilise mood.
- Warfarin (prevents blood clots), increased risk of bleeding with products that have a coumarin component (black cohosh, chamomile) or antiplatelet effects (billberry leaf, fish oil, vitamin E and ginger, garlic), cranberry.
- St John’s Wort and certain antidepressants, can cause ‘serotonin syndrome’ a serious condition marked by confusion, uncoordination, and cardiovascular irregularities.St John’s Wort and sunlight can cause photosensitivity, especially if combined with other photosensitizing drugs like certain antibiotics.In addition, fatigue and gastrointestinal upset occur in some people. Avoid standardized St. John’s Wort if you use tanning beds or take drugs that cause photosensitivity (You might get burned!).
- Preliminary research suggests high doses of St. John’s Wort may also increase the risk of sun-induced cataracts.
- Kava & Sleeping tablets – increases sedation leading to coma.Kava Kava has become the herbal answer to Valium in America. Kava helps calm the mind and relax the muscles without causing side effects like over-sedation or addiction.However, kava is not safe for everyone. Don’t take kava with alcohol as it can intensify the effects of alcohol. In addition, kava may interact with anti-anxiety medications like, benzodiazepines and anaesthetics. Kava should also be avoided by people taking anti-psychotic drugs and levodopa for Parkinson’s disease.
- Recent media reports suggest kava causes liver damage. However, new evidence shows in 27 of the 30 reported cases the people were using other medications or had a history of alcoholism which may have contributed to the liver toxicity. (In the South Pacific where kava is used regularly in high doses, there are few reports of liver toxicity.) Still, until we know more, avoid kava when you drink alcohol, or if you have liver problems, or if you take drugs that affect the liver. Note: Discontinue kava use if you experience warning signs of jaundice like yellowing of the eyes.
- Gingko & Aspirin – increases inhibition of platelet aggregation (a blood component) leading to increased bleeding, bruising (Gingko can be used for vascular insufficiency, poor circulation, stress and tinnitus. It is also a neroprotective and antioxidant, helps to improve concentration).
- St John’s Wort & Digoxin – reduces absorption of digoxin leading to decreased digoxin level.
- Garlic & Warfarin – increases inhibition of platelet aggregation leading to increased bleeding, bruising (Garlic for high cholesterol and blood pressure).
- Gingko & Warfarin – increases inhibition of platelet aggregation (a blood component) leading to increased bleeding, bruising. Widely used to help reduce age–related problems like poor circulation, heart disease, tinnitus and impotence, ginkgo is best known as an effective herbal brain booster against memory deterioration. While generally very safe, ginkgo’s blood–thinning effects can interact with some anticoagulants like warfarin and aspirin.
- Ginseng & Warfarin – increased risk for blood clots (Ginseng for cognitive function and concentration. a herb to restore and normalize various body functions like blood pressure, blood sugar, energy, and endurance. Ginseng is the only plant known that contains phyto-testosterone which stimulates sex drive in both men and women!Ginseng may not be appropriate for everyone. A new report suggests that patients with bipolar disorder on antidepressant drug therapy should avoid ginseng as it may provoke a manic state.
- Feverfew and anti–inflammatories: Traditional herbalists turn to feverfew for migraine relief and to reduce migraine–related symptoms like nausea, vomiting and sensitivity to light.A combination of anti-inflammatories and feverfew may increase the risk of stomach irritation because both substances affect prostaglandins that protect the stomach lining. (Anti–inflammatories by themselves are a clear risk factor for stomach ulcers.) Feverfew can also affect blood clotting. Use with caution if you take warfarin.
- Potassium wasting medications (steroids, diuretics) – aloe and liquorice both increase potassium loss leading to low potassium levels (muscle weakness, myalgia, cramps, heart palpitations).
- Immunosuppressant‘s (drugs used to prevent rejection in organ transplants –cylosporin, azathioprine). Echinacea decreases immunosuppressant effect. Avoid Echinacea in auto immune disease i.e. multiple sclerosis. High doses of Echinacea over a long time may become less effective, better to have breaks.
- Sedatives (benzodiazepines, barbiturates) with valerian, ginger, chamomile – increases sedative effect.
- Hypoglycaemic agents (used to reduce blood sugars, metformin, and insulin). Ginseng – decreases glucose levels, monitor blood sugars routinely.
- Antihypertensives (lower blood pressure) – black cohosh can cause a decrease in blood pressure. Liquorice can cause increased sodium and water rentention – which can lead to an increase in blood pressure; most people can take liquorice without problems, but avoid it if you have high blood pressure or if you take high blood pressure drugs.In very high doses, the liquorice constituent, glycyrrhizin, can cause potassium loss, fluid retention and elevated blood pressure. Liquorice is not advised for people with a history of renal failure or who take heart medication or steroid drugs.
Herbal medicines can affect sedation, pain control, bleeding, heart function, metabolism, immunity and recovery. Therefore it is very important to inform your Doctor if going for a surgical procedure.
Discontinuation time varies according to the herbal medicine.
- Garlic – risk of bleeding discontinue 7 days before surgery.
- Echinacea – allergic reactions, impairs immune suppressive drugs, can impair wound healing, discontinue at least 2 weeks, longer if having organ transplant.
- Gingko – risk of bleeding, discontinue at least 36 hours before surgery.
- Ginseng – lowers blood sugar levels, increase risk of bleeding, discontinue 7 days before surgery.
- Kava – increase in sedative effects of anaesthesia. Discontinue at least 24 hours before surgery.
- St John’s Wort – alters metabolism of other drugs. Discontinue at least 5 days before surgery.
- Valerian – long term use could increase the amount of anaesthesia needed. Discontinue a few weeks before, taper dose.
- Echinacea and antibiotics – decreases the side effect of thrush.
- Ginkgo and antidepressants – helps with sexual dysfunction.
- Milk thistle when taking medicines that elevates liver enzymes or stress the liver detoxification pathways.
- B–complex vitamins are widely known to reduce drug-induced nutrient depletion from medications like oral contraceptives, oestrogen replacement drugs, and methotrexate.
In New Zealand the Centre for Adverse Reactions Monitoring (CARM) in Dunedin is responsible for collating information on adverse reactions and interactions, at the moment the reporting rate is relatively low. Most likely due to under reporting.
Herbal remedies are not classifieds as medicines and therefore do not come under the same regulations governing modern medicines.
However there are standards for good manufacturing practices that responsible manufacturers will adopt. They should be test for purity, standardisation and batch to batch consistency.
Herbal medicines can not claim cures for aliments on the packaging. However they often provide information such as ‘may assist in the management of ….’
Gail Edwards MPS, ANZCP
- Natural Therapeutics Pocket Guide: Lexi-Comp 2nd Edn.
- Pharmacy Today August 2007.
- Stockley’s Drug Interactions 7th Edn. Pharmaceutical press.
- Medicines Information Bulletin, Dunedin information service, Dunedin Hospital. May 2000
- Checking for possible herb-drug interactions: Subhuti Dharmananda, Ph.D, Institute for Traditional Medicine, Portland, Oregon
- Herbal Interactions, Jo Barnes. Pharmaceutical Journal 25/1/03
- Herbals, Evidence and Interactions, Phil Rassmussen. NZ College of Pharmacists, 2003
- Medsafe website. http://www.medsafe.govt.nz/regulatory/compmed.asp