Allercy and Asthma Health
The Official Publication of AAN - MA

Decreasing the Risk of Food-Related Allergies and Drug Interactions


by Patricia Beck Koff, MEd, RRT

peanutsAs we think about our respiratory patients and the problems that can affect them, several food-drug interactions are important to consider. Even in the best of circumstances, some foods can increase the potency of medications; some can interfere with the uptake of them and reduce the potency. Certain combinations can even be life threatening. The more that you, as a patient, know about this, the more we are able to help you minimize problems. Some problems with foods are avoided by inhaling your drugs, since the stomach and intestines (sites of drug absorption) are bypassed.

This article cannot really begin to cover all interactions, but I hope it will increase your awareness of potential problems and motivate you to ask more questions of your health care provider and do more searching for information on your own.

Peanut/soy lecithin
Perhaps one of the most important food-drug interactions for lung patients is related to peanut allergies. Any of our patients who have an allergy to peanuts should check their  ipratropium bromide (Atrovent®) and ipratropium bromide/albuterol sulfate (Combivent®) inhalers. Both of the older versions of these inhalers have a propellant that contains soya lecithin, so anyone with sensitivities to soy or soy-related products, like peanuts, may be affected. (Consult with your pharmacist about the inhaler that you are using.) The solution forms of these medications do not have the propellant  and so they are considered safe.

Milk or dairy products
The use of tiotropium (Spiriva®), the drug for people with COPD, may need to be reconsidered if someone has a hypersensitivity to milk proteins. Lactose monohydrate (milk sugar) is used in the powder capsules that are placed in the inhaler device. This product is used in other medications as well; the substance helps improve the compressibility and dissolving properties of medications. In addition to the allergic reaction, dairy products are also known to interfere with certain antibiotics. The calcium of dairy products binds with tetracyclines in the stomach, and the body cannot effectively use the calcium or the tetracycline. Dairy is also not recommended with the drugs such as Levaquin®, or Cipro®.

Chocolate can be full of helpful antioxidants, especially if  you're eating the dark chocolate. But it also has a few problem qualities. Tyramine and caffeine are found in chocolate and discussed below.

Beta agonists, which include many medications for asthma and COPD, are likely to make people become nervous (develop tremors or shakiness) or anxious. Too much caffeine can have the same effect. The two used together can cause discomfort sooner than either alone. Remember, the strength of coffees vary considerably, and tea contains a caffeine-like substance, as does chocolate and most soft drinks.

We often recommend that people with cardiopulmonary problems receive seasonal flu vaccinations. Most vaccines are grown in eggs and, consequently, if someone is allergic to eggs, they should not receive the vaccine. An exception to this may be the pneumococcal vaccine; conflicting information exists related to eggs and the pneumonia shot's safety, so it's best to check with your doctor.

Grapefruit and fruit juices
Probably the most frequent food-drug interaction today is grapefruit and grapefruit juice. Grapefruit can be an issue to our pulmonary patients who frequently also have hypertension and/or high cholesterol. Some medications that treat those two problems (as well as many other drugs) may have increased potency by the interaction of substances called furanocoumarins within grapefruit. The furanocoumarins inhibit enzymes that are responsible for the intestinal processing of the medications. As a consequence, the drugs enter the bloodstream faster, and the potency is increased.

It is best to ask your doctor if your specific medications are affected by grapefruit, grapefruit juice, or other citric products. For example, the antihistamine fexofenadine (Allegra®) has decreased absorption if taken with apple, orange, or grapefruit juice; and some macrolide antibiotics also should not be taken with citrus juices. Another possible pathway that is altered by grapefruit juice is the liver's "cytochrome P-450" enzyme system and, consequently, the metabolism of the medication through the liver.

Perhaps in the not-too-distant future, grapefruit juice will be produced as "furanocoumarin free." The opposite possibility exists: Maybe we will someday be telling people to "drink grapefruit juice" to enhance absorption of oral medications. For now, it is best to avoid grapefruit if taking statins for cholesterol control: simvastatin (Zocor®), lovastatin (Mevacor®), and atorvastatin (Lipitor®). Double check your hypertension medications for grapefruit interactions, too. Your health care provider or a pharmacist can provide more information or medication literature to inform you about these interactions.

Tyramine is a substance found in many foods, including aged cheese, red wines, some processed meat, sauerkraut, chocolate, and tap beer. It can increase blood pressure and heart rate as well as cause other problems. Anyone taking a monoamine oxidase inhibitor (MAOI) for depression, such as phenelzine (Nardil®), tranylcypromine (Parnate®), isocarboxazid (Marplan®), or selegiline (Eldepryl®) should avoid foods that are rich in tyramine.

High levels of tyramine can cause dangerously high blood pressure (possibly strokes) and severe headaches. Almost half of all COPD patients suffer from depression. Although many are not treated or are treated with drugs that are different from this class, you and your doctor should be aware of the problems created by them.

Believe it or not, this seemingly simple snack can be risky with several medications. Licorice is made from a plant root; and while it can have some medicinal properties, it can also have negative interactions with many prescription medications. It may cause electrolyte disturbances, as well as potassium levels, to fall if used with diuretics such as Lasix® and it may reduce the effects of hypertension medications. It can also interact with the depression medications. Licorice may increase the effects of corticosteroids used for controlling asthma. Anyone with congestive heart failure or who take diuretics should use it cautiously if at all. It should not be used at all with digoxin (Lanoxin®) due to the risk of toxic side effects. Deglycyrrhizinated licorice has had the acid removed and is considered safer to use.

Another consumable that has an especially concerning effect with many medications is alcohol. Alcohol can produce liver damage, which interferes with the clearance of medications. It can also enhance the effect of sedatives and narcotics; this interaction has the potential to create a drug overdose and even death.

The use of antihistamines and alcohol is also discouraged for the same enhancing effect. Antibiotics and alcohol are also discouraged. The side effects of alcohol (e.g., headache, dizziness, nausea, stomach pain) are similar to those of some antibiotics, so the combination of the two can lead to major side-effect problems. This is especially true with metronidazole (Flagyl®), tinidazole (Tindamax®), and trimethoprim-sulfamethoxazole (Bactrim™).

Inhaled steroid doses are probably the main concern for people who smoke. If you smoke, medication doses may need to be increased, so talk with your doctor. If you stop smoking, dosages of various drugs may need to be decreased.

Bottom line: Smoking cessation needs to be considered in achieving appropriate medication levels and to improve your overall health and lung function.

Mind your medications
Finally, here are a couple of last notes on food-related issues. Appetites are sometimes suppressed by a dry mouth. Dry mouth can be a side effect of (Atrovent), ipratropium bromide/albuterol sulfate (Combivent), and tiotropium (Spiriva). This can become a major issue for undernourished COPD patients or others taking the medication. Moistening drops may be helpful, so check with your health care provider.

Also, many foods are best absorbed on empty stomachs while other foods are absorbed best with food. The type of appropriate food may also be a consideration (medications taken with high-fat meals allow for slower absorption, which may be positive or negative depending on the medication). Consulting with your doctor or pharmacist with any new prescription makes sense. Also, using one pharmacy for all medications can help to avoid problems.

In closing, the "eat, drink, and be merry" adage is good advice, but also be careful to "mind your medications." •

Additional Information

  • Combivent web site. Important information on how to take your Combivent Inhalation Aerosol. Available at
  • web site. A corn starch/a-lactose monohydrate compound as a directly compressible excipient. Available at:
  • U.S. Food and Drug Administration web site. Avoiding drug interactions. Available at:
  • Paine MF, Widmer WW, Hart HL, et al. A furanocoumarin-free grapefruit juice establishes furanocoumarins as the mediators of the grapefruit juice-felodipine interaction. Am J Clin Nutr 2006; 83(5):1097-1105.
  • Lin HL, Kent UM, Hollenberg PF. The grapefruit juice effect is not limited to cytochrome P450 (P450) 3A4: evidence for bergamottin-dependent inactivation, heme destruction, and covalent binding to protein in P450s 2B6 and 3A5. J Pharmacol Exp Ther 2005; 313(1):154-164.
  • Norwood R. Psychosocial aspects of chronic obstructive pulmonary disease. In: Voelkel NF, McNee W, editors. Chronic obstructive lung diseases 2. Hamilton Ontario: BC Decker Inc; 2008.
  • National Institute on Alcohol Abuse and Alcoholism (National Institutes of Health) web site. Harmful interactions: mixing alcohol with medicines. Available at:

Patricia Beck Koff, MEd, RRT, is a respiratory therapist and affiliate faculty member of the University of Colorado's department of pulmonary sciences and critical care medicine in Aurora, CO.  She also recently joined the staff of Robert Bosch with the Medicare High Cost Demonstration Project.  

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