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Drug Interactions - Medication Reactions - Drugs Not to Mix


Updated June 10, 2014

How can I avoid harmful drug interactions?

Make sure your doctor knows about every drug you are taking, including drugs you obtain without a prescription order. If you have any problems related to medication, call your physician or pharmacist immediately. One drug may interact with another, in some cases creating serious medical problems. This information does not cover the interaction of one medicine with another. Additionally, interactions will vary according to the dosage, your age, sex and your overall health.


  • It is a good rule of thumb to avoid consuming alcohol while taking any drug unless a physician or pharmacist indicates that the combination is acceptable.

  • Cigarettes can also diminish the effectiveness of medication or create added hazards with certain medications.

  • Caffeine, which is found in coffee, tea, soft drinks and chocolate and some medications, can also affect the action of some drugs.

  • Medication should never be taken during pregnancy without the advice of your physician.



Antihistamines are used to relieve or prevent the symptoms of colds and hay fever and other types of allergy. They act to limit or block histamine which is released by the body when we are exposed to substances that cause allergic reactions.

Some commonly used antihistamines:

  • brompheniramine/Dimetane
  • Bromphen
  • chlorpheniramine/Chlor-Trimeton
  • Teldrin
  • diphenhydramine/Benadryl
  • Benaphen

INTERACTION--Avoid taking with alcoholic beverages because antihistamines combined with alcohol may cause drowsiness and slowed reactions.


Bronchodilators are used to treat the symptoms of bronchial asthma, chronic bronchitis and emphysema. These medicines relieve wheezing, shortness of breath and troubled breathing. They work by opening the air passages of the lungs.

Some commonly used bronchodilators:

  • aminophylline/Phyllocontin
  • Somophyllin
  • theophylline/Slo-Phyllin
  • Theo-Dur

INTERACTION--Avoid eating or drinking large amounts of foods or beverages which contain caffeine because both bronchodilators and caffeine stimulate the central nervous system.

Many over the counter cold remedies contain aspirin in combination with other active ingredients.



Aspirin reduces pain, fever and inflammation. Aspirin is available in many brands.

INTERACTION--Because aspirin can cause stomach irritation, avoid alcohol. To avoid stomach upset, take with food. Do not take with fruit juice.


--Cortisone-like drugs are used to provide relief to inflamed areas of the body. They lessen swelling, redness, itching and allergic reactions.

Some commonly used steroids:

  • betamethasone
  • dexamethasone
  • hydrocortisone
  • methylprednisolone
  • prednisone
  • triamcinolone

INTERACTION--Avoid alcohol because both alcohol and corticosteroids can cause stomach irritation. Also avoid foods high in sodium (salt). Check labels on food packages for sodium. Take with food to prevent stomach upset.

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