Medicine - Herb/Food Interactions

Many people have the mistaken notion that, being natural, all herbs and foods are safe. This is not so. Very often, herbs and foods may interact with medications you normally take that result in serious side reactions. It is always a good practice to tell your doctor or health practitioners what you are taking so that they can advise you of possible complications, if there is any. You should also keep an eye for unusual symptoms. Very often, this may foretell the symptoms of a drug interaction.

Experts suggest that natural does not mean it is completely safe. Everything you put in your mouth has the potential to interact with something else. The medication that is taken by mouth travels through the digestive system in much the same way as food and herbs taken orally do. So, when a drug is mixed with food or another herb, each can alter the way the body metabolizes the other. Some drugs interfere with the body's ability to absorb nutrients. Similarly, some herbs and foods can lessen or increase the impact of a drug.

Alcohol is a drug that interacts with almost every medication, especially antidepressants and other drugs that affect the brain and nervous system.
Some dietary components increase the risk of side effects. Theophylline, a medication administered to treat asthma, contains xanthines, which are also found in tea, coffee, chocolate, and other sources of caffeine. Consuming large amounts of these substances while taking theophylline increases the risk of drug toxicity.
Certain vitamins and minerals impact on medications too. Large amounts of broccoli, spinach, and other green leafy vegetables high in vitamin K, which promotes the formation of blood clots, can counteract the effects of heparin, warfarin, and other drugs given to prevent clotting.
Dietary fiber also affects drug absorption. Pectin and other soluble fibers slow down the absorption of acetaminophen, a popular painkiller. Bran and other insoluble fibers have a similar effect on digoxin, a major heart medication.

As more and more people discover new herbs, there is more and more potential for the abuse of these herbs and the patients may end up in serious problems. High-risk patients, such as the elderly, patients taking three or more medications for chronic conditions, patients suffering from diabetes, hypertension, depression, high cholesterol or congestive heart failure, should be especially on the lookout for such side reactions.

The following are the examples of known interaction between popular herbs, foods, and prescription and over-the-counter drugs.

Hawthorn, touted as effective in reducing angina attacks by lowering blood pressure and cholesterol levels, should never be taken with Lanoxin (digoxin), the medication prescribed for most for heart ailments. The mix can lower your heart rate too much, causing blood to pool, bringing on possible heart failure.

Ginseng, according to research, can increase blood pressure, making it dangerous for those trying to keep their blood pressure under control. Ginseng, garlic or supplements containing ginger, when taken with the blood-thinning drug, Coumadin, can cause bleeding episodes. Coumadin is a very powerful drug that leaves little room for error, and patients taking it should never take any medication or otherwise before consulting a qualified health professional. In rare cases, ginseng may overstimulate resulting in insomnia. Consuming caffeine with ginseng increases the risk of overstimulation and gastrointestinal upset. Long tern use of ginseng may cause menstrual abnormalities and breast tenderness in some women. Ginseng is not recommended for pregnant or lactating women.

Garlic capsules combined with diabetes medication can cause a dangerous decrease in blood sugars. Some people who are sensitive to garlic may experience heartburn and flatulence. Garlic has anti-clotting properties. You should check with your doctor if you are taking anticoagulant drugs.

Goldenseal is used for coughs, stomach upsets, menstrual problems and even arthritis. However, the plant's active ingredient will raise blood pressure, complicating treatment for those taking antihypertensive medications, especially beta-blockers. For patients taking medication to control diabetes or kidney disease, this herb can cause dangerous electrolyte imbalance. High amount of consumption can lead to gastrointestinal distress and possible nervous system effects. Not recommended for pregnant or lactating women.

Feverfew, believed to be the natural remedy for migraine headaches, should never be taken with Imitrex or other migraine medications. It can result in the patient's heart rate and blood pressure to rise dangerous levels.

Guarana, an alternative remedy being used as a stimulant and diet aid, contains 3 percent to 5 percent more caffeine than a cup of coffee. So, if you are taking any medication that advises you against taking any drink with caffeine, you should avoid taking this stimulant. It may cause insomnia, trembling, anxiety, palpitations, urinary frequency, and hyperactivity. Avoid during pregnancy and lactation period. Long term use of Guarana may lead to decreased fertility, cardiovascular disease, and several forms of cancer.

Kava, a herb that has antianxiety, pain relieving, muscle relaxing and anticonvulsant effects, should not be taken together with substances that also act on the central nervous system, such as alcohol, barbiturates, anti depressants, and antipsychotic drugs.

St. John's Wort is a popular herb used for the treatment of mild depression.

The active ingredient of St. John's Wort is hypericin. Hypericin is believed to exert a similar influence on the brain as the monoamine oxidase (MAO) inhibitors such as the one in major antidepressants. Mixing MAO inhibitors with foods high in tyramine, an amino acid, produces one of the most dramatic and dangerous food-drug interactions. Symptoms, which can occur within minutes of ingesting such foods while taking an MAO inhibitor, include rapid rise in blood pressure, a severe headache, and perhaps collapse and even death. Foods high in tyramine include aged cheese, chicken liver, Chianti (and certain other red wines), yeast extracts, bologna (and other processed meats), dried or pickled fish, legumes, soy sauce, ale, and beer.

Some patients report that Saint Johns Wort caused excessive stimulation and sometimes dizziness, agitation and confusion when taken with other antidepressants or over-the-counter medications like Maximum Strength Dexatrim and Acutrim. It also caused their blood pressure to shoot up.

White Willow, an herb traditionally used for fever, headache, pain, and rheumatic complaints may lead to gastrointestinal irritation, if used for a long time. It exhibits similar reactions as aspirin (aspirin is derived from white willow). Long term use may lead to stomach ulcers.

Drug Interaction and Food

Drug interaction risk isn't limited to herbal supplements. Certain foods can interact with medications.

People taking digoxin should avoid Black licorice (which contains the ingredient glycyrhizin). Together, they can produce irregular heart rhythms and cardiac arrest; licorice and diuretics will produce dangerously low potassium levels, putting a patient at risk for numbing weakness, muscle pain and even paralysis. Licorice can also interact with blood pressure medication or any calcium channel blockers.

Aged cheese (brie, parmesan, cheddar and Roquefort), fava beans, sauerkraut, Italian green beans, some beers, red wine, pepperoni and overly ripe avocados should be avoided by people taking MAO antidepressants. The interaction can cause a potentially fatal rise in blood pressure.

And because Saint Johns Wort contains the same properties as these MAO antidepressants, it stands to reason that people ingesting the herb should avoid these same foods.

Grapefruit juice interacts with calcium channel blockers (including Calan, Procardia, Nifedipine, and Verapamil), cholesterol control medications, some psychiatric medications, estrogen, oral contraceptives and many allergy medications (Seldane, Hismanal). The juice modifies the body's way of metabolizing the medication, affecting the liver's ability to work the drug through a person's system. More Information.

Orange juice shouldn't be consumed with antacids containing aluminum. 'The juice increases the absorption of the aluminum. Orange Juice and milk should be avoided when taking antibiotics. The juice's acidity decreases the effectiveness of antibiotics, as does milk.

Milk also doesn't mix with laxatives containing bisacodyl (Correctol and Dulcolax). You might find the laxative works a little "too well" in the morning.

Large amounts of oatmeal and other high-fiber cereals should not be eaten when taking digoxin. The fiber can interfere with the absorption of the drug, making the act of swallowing the pill a waste of time.

However, don't stop eating your cereal right away, because that could cause digoxin levels in your system to soar to toxic levels. A professional should make the dietary changes after carefully examining the digoxin levels.

Leafy green vegetables, high in vitamin K, should not be taken in great quantities while taking Coumadin. These vegetables could totally negate the affects of the drug and cause blood clotting.

Caffeinated beverages and asthma drugs taken together can cause excessive excitability. Those taking Tagament (Simetidine), quinolone antibiotics (Cipro, Penetrex, Noroxin) and even oral contraceptives should be aware these drugs may cause their cup of coffee to give them more of a Java jolt than they expected.

Grilled meat can lead to problems for those on asthma medications containing theophyllines. The chemical compounds formed when meat is grilled somehow prevent this type of medication from working effectively, increasing the possibility of an unmanageable asthma attack.

Regularly consuming a diet high in fat while taking anti-inflammatory and arthritis medications can cause kidney damage and can leave the patient feeling, drowsy and sedated.

Alcoholic beverages tend to increase the depressive effects of medications such as benzodiazepines, antihistamines, antidepressants, antipsychotics, muscle relaxants, narcotics, or any drug with sedative actions.

It's a good idea to not consume any alcoholic beverages, or at least scale way back, when taking prescription medications. Antioxidant and beta-carotene intensify alcohol's effect on the liver.

Other commonly used over-the-counter medications can cause interaction problems also.

Aspirin can modify the effectiveness of arthritis medications, strong prescription steroids and diuretics. Combining aspirin with diabetic medications can drop blood sugars to dangerous levels. Aspirin can also cause toxicity when taken with glaucoma and anticonvulsant (anti-seizure) drugs and cause bleeding episodes when combined with a blood thinner, like Coumadin.

Acetaminophen can also cause interaction complications when overused. Heavy drinkers who take acetaminophen for hangover relief risk liver damage. Taking high doses of acetaminophen with Coumadin can cause bleeding episodes.

Antacids taken with antibiotics, heart and blood pressure or thyroid medications can decrease drug absorption by up to 90 percent.

Over-the-counter antihistamines - sold under the names Actifed, Theraflu, Dimetapp, Benadryl and Comtrex should be avoided if you are taking antianxiety or antidepressant medications.

Oral contraceptives are less effective when taken with barbiturates, antibiotics, anti-fungal or tuberculosis drugs.

Turnips contain two goitrogenic substances, progoitrin and gluconasturtin, which can interfere with the thyroid gland's ability to make its hormones. Although moderate consumption of goitrogens is not a hazard for healthy people, they can promote development of a goiter (an enlarged thyroid) in persons with thyroid disease.

Tomato contains small quantities of a toxic substance known as solanine that may trigger headaches in susceptible people. They are also a relatively common cause of allergies. An unidentified substance in tomatoes and tomato-based products can cause acid reflux, leading to indigestion and heartburn. Individuals who often have digestive upsets should try eliminating tomatoes for 2 to 3 weeks to see if there is any improvement.

Strawberries, Raspberries, Spinach, and Rhubarb: These contain oxalic acid, which can aggravate kidney and bladder stones in susceptible people, and reduce body's ability to absorb iron and calcium.

Raspberries contain a natural salicylate that can cause an allergic reaction in aspirin sensitive people.

The seeds from fruits such as Apple, apricot, and Quinces contain amygdalin, a compound that turns into Hydrogen Cyanide in the stomach. Eating large amount of seeds can result in cyanide poisoning.

Potatoes: Avoid potatoes with a green tint to the skin, and remove any sprouts; they will taste bitter and may contain solanine, a toxic substance that can cause diarrhea, cramps, and fatigue.

Plums, Peaches, Apricots, and Cherries: These fruits may produce allergic reaction in individuals with confirmed allergies to apricots, almonds, peaches, and cherries. People who are allergic to aspirin may also encounter problems after they have eaten plums or peaches as they contain salicylates. The pits of plums, peaches and apricots contain a compound called amygdalin. When consumed in large amounts, amygdalin breaks down into hydrogen cyanide, a poison.

Horseradish: Very high doses of horseradish can cause vomiting or excessive sweating. Avoid if you have hypothyroidism.

Turmeric: Should be avoided by persons with symptoms from gallstones.

The drug food interaction is summarized below.


Cephalosporins, penicillin
Take on an empty stomach to speed absorption of the drugs.

Erythromycin
Don't take with fruit juice or wine, which decrease the drug's effectiveness.

Sulfa drugs
Increase the risk of Vitamin B-12 deficiency

Tetracycline
Dairy products reduce the drug's effectiveness. Lowers Vitamin C absorption

Dilantin, phenobarbital
Increase the risk of anemia and nerve problems due to deficiency of folalte and other B vitamins.

Fluoxetine
Reduce appetite and can lead to excessive weight loss

Lithium
A low-salt diet increases the risk of lithium toxicity; excessive salt reduces the drug's efficacy

MAO Inhibitors
Foods high in tyramine (aged cheeses, processed meats, legumes, wine, beer, among others) can bring on a hypertensive crisis.

Tricyclics
Many foods, especially legumes, meat, fish, and foods high in Vitamin C, reduce absorption of the drugs.

ACE inhibitors
Take on an empty stomach to improve the absorption of the drugs.

Alpha blockers
Take with liquid or food to avoid excessive drop in blood pressure.

Antiarrhythmic drugs
Avoid caffeine, which increases the risk of irregular heartbeat.

Beta blockers
Take on an empty stomach; food, especially meat, increases the drug's effects and can cause dizziness and low blood pressure.

Digitalis
Avoid taking with milk and high fiber foods, which reduce absorption, increases potassium loss.

Diuretics
Increase the risk of potassium deficiency.

Potassium sparing diuretics
Unless a doctor advises otherwise, don't take diuretics with potassium supplements or salt substitutes, which can cause potassium overload.

Thiazide diuretics
Increase the reaction to MSG.

Pseudoephedrine
Avoid caffeine, which increase feelings of anxiety and nervousness.

Theophylline
Charbroiled foods and high protein diet reduce absorption. Caffeine increases the risk of drug toxicity.

Cholestyramine
Increases the excretion of folate and vitamins A, D, E, and K.

Gemfibrozil
Avoid fatty foods, which decrease the drug's efficacy in lowering cholesterol.

Antacids
Interfere with the absorption of many minerals; for maximum benefit, take medication 1 hour after eating.

Cimetidine, Fanotidine, Sucralfate
Avoid high protein foods, caffeine, and other items that increase stomach acidity.

Oral contraceptives
Salty foods increase fluid retention. Drugs reduce the absorption of folate, vitamin B-6, and other nutrients; increase intake of foods high in these nutrients to avoid deficiencies.

Steroids
Salty foods increase fluid retention. Increase intake of foods high in calcium, vitamin K, potassium, and protein to avoid deficiencies.

Thyroid drugs
Iodine-rich foods lower the drug's efficacy.

Laxative Mineral Oils
Overuse can cause a deficiency of vitamins A, D, E, and K.

Painkillers
Aspirin and stronger non-steroidal anti-inflammatory drugs Always take with food to lower the risk of gastrointestinal irritation; avoid taking with alcohol, which increases the risk of bleeding. Frequent use of these drugs lowers the absorption of folate and vitamin C.

Codeine
Increase fiber and water intake to avoid constipation.

Benzodiazepines
Never take with alcohol. Caffeine increases anxiety and reduce drug's effectiveness.

Medicines and Food

Almost every patient and some doctors have this doubt: When should a particular medicine be taken? Before, With or After Food. This blog attempts to clear the fog.

Food can affect some medicines. Therefore often your medicine label may note "take with food", "take on an empty stomach" or "take half an hour before food". For many medicines that you take every day it is best to take them at the same time in relation to food every day.

Common instructions about medicines and foods and usual explanations are as follows:

Take with food
In most cases the medicine can be taken during the meal or immediately after the meal. There may be two reasons for this instruction, either the medicine can cause a stomach upset if you take it without food (e.g. doxycycline, Augmentin), or food will make the medicine be absorbed better into the body (e.g. griseofulvin)

Take after food
This may be for the same reasons as take with food. In the case of Gaviscon, it is used after food so that it works better to stop the food coming up from the stomach into the oesophagus (gullet).

Take on an empty stomach
In most cases the medicine should be taken at least two hours after the last time you ate and at least one hour before you are going to eat again. Examples include flucloxacillin, and antibiotic that doesn't work nearly as well if you have it with food, and etidronate.

For some medicines even the smallest amount of food in the stomach greatly reduces the amount of medicine that passes into the bloodstream. A group of medicines called bisphosphonates, used to treat conditions such as osteoporosis, are a particular problem. They include: alendronate, clodronate, etidronate and risedronate.

For medicines that must be taken on an empty stomach so that they pass into the bloodstream properly, you should choose times of the day that are convenient to you. Before breakfast is ideal for once daily medicines, but other good times include mid-morning, mid-afternoon and last thing at night. Bisphosphonate medicines (see above) should not be taken at bedtime.


This instruction is because the medicine is not absorbed as well by the body if you have much food in your stomach. In some cases the medicine may bind with something in the food. In other cases there is a special coating (enteric coating) on the tablet that does not dissolve until it gets into the intestine, so if you take the medicine with a big meal it can take many hours to start working (e.g. anti-inflammatories with an enteric coating).

Medicines generally work faster if taken on an empty stomach, so some pain relievers may be recommended to be taken before food.

Do not take grapefruit or grapefruit juice while taking medicine. In the last couple of years grapefruit have been found to alter the levels of some medicines in the body. In some cases the amount of the medicine in the blood can be increased by as much as 16 times the usual amount. So, if this instruction is on the label of your medicine you are best to avoid grapefruit and grapefruit juice completely.

Enzymes in the wall of the gut change some medicines on the way through into the bloodstream, making them less active. Grapefruit juice blocks these enzymes so medicines that would normally be changed instead arrive intact in the bloodstream in greater amounts than expected.

Avoid certain foods with certain medicines
Monoamine oxidase inhibitors such as tranylcypromine (Parnate) or phenelzine (Nardil) have special instructions with respect to foods. Many foods need to be avoided including cheese, sour cream, yeast and meat extracts, liver, sherry, beer (even non-alcoholic), red wine, avocados, chocolate, soy beans, broad bean pods, meals prepared with tenderisers, pickled fish, canned figs. Your pharmacist or doctor will be able to give you a more complete list.

Do not take antacids that contain magnesium or aluminum (e.g., Gelusil), the ulcer medicine sucralfate (Sucrafil), or vitamin or mineral supplements that contain iron or zinc for a minimum of 2 hours before or 2 hours after a dose of medicine. Taking antacids, sucralfate, or vitamin or mineral supplements too close to a dose of medicine can greatly decrease the effects of the medicine.

Common medicines taken with food

• Anti-diabetics such as glibenclamide and metformin
• Anti-inflammatories or NSAIDs (e.g. Voltaren, Naprosyn), unless enteric coated, or a quick effect is required.
• Steroids e.g. prednisone, prednisolone, hydrocortisone
• Adalat (nifedipine)
• Augmentin (amoxicillin + clavulanic acid)
• Aspirin in high doses
• Daonil (glibenclamide)
• Diamicron (gliclazide)
• Epilim (sodium valproate)
• EES (erythromycin ethyl succinate)
• Fergon (iron)
• Ferrogradumet (iron)
• Flagyl (metronidazole)
• Glucophage (metformin)
• Griseofulvin
• Lanoxin (digoxin)
• Lithicarb (lithium)
• Megostat (megestrol)
• Minidiab (glipizide)
• Mino-tabs (minocycline)
• Naprosyn (naproxen)
• Nifuran (nitrofurantoin)
• Nolvadex (tamoxifen)
• Nuelin (theophylline)
• Priadel (lithium)
• Roaccutane (isotretinoin)
• Salazopyrin (sulphasalazine)
• Slow K (potassium)
• Sporanox (itraconazole)
• Theo-dur (theophylline)
• Vermox (mebendazole)
• Vibra-tabs (doxycycline)
• Voltaren (diclofenac)
• Zinc
• Zyloprim (allopurinol)

Common medicines taken on an empty stomach

• Flucloxacillin
• Penicillamine
• Levothyroxine (thyroxine)
• Penicillin v phenoxymethylpenicillin)
• Oxytetracycline
• Bidanzen (serratio-peptidase)
• Capoten (captopril)
• Didronel (etidronate)
• ERA (erythromycin stearate)
• ERYC (erythromycin base)
• Floxapen (flucloxacillin)
• Norflox (norfloxacin)
• Omez (omeperazole)
• Rifampicin
• Selectol (celiprolol)
• Sucralfate
• Mebeverine
• Sodium cromoglicate

Examples of medicines that don't mix well with grapefruit juice

• Halcion (triazolam)
• Isoptin (verapamil)
• Plendil (felodipine)
• Prepulsid (cisapride)
• Zocor (simvastatin)

Hope this helps!