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The Consumer’s Guide To Drug Interactions

Dr. Munir Hussain

3 min read

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With multiple medical conditions come multiple medications; many of which can react either with each other, consumed food or drink, or the body itself to produce ‘drug interactions’. While some of these interactions might simply reduce a particular drug’s effectiveness, others may lead to serious complications. Considering that adverse interactions are a major cause of hospitalization, doctors educating patients on drug reactions is highly imperative.

How They Happen:

Certain medication, foods, or bodily processes stimulate or inhibit specific enzymes (substances used to initiate chemical reactions) that aid in the metabolization (breakdown) of many medications in the liver or intestine to either prolong or accelerate the metabolization of a particular drug.


Depending upon the causative agent, drug interactions are divided into 3 categories:

1- Drug-Drug Interactions (DDI)

They occur when one or more drugs, classified as ‘precipitant drugs’ affect the metabolization of the other drug, aka ‘object drug’, which can either suppress the object drug’s effectiveness, cause negative side effects, or combine with it to amplify their effects; resulting in an ‘overdose’ of sorts.

For instance, sedatives (sleep medication) alongside an anti-allergy drug can result in drowsiness and delayed reaction, or taking painkillers (paracetamol, ibuprofen, etc.) alongside blood-thinning medications combines the anti-clotting actions of both to result in severe bleeding in case of an injury.

2- Drug-Food/Supplement Interactions

Certain foods or nutritional supplements can also block or stimulate the cytochrome enzyme reactions over specific drugs to cause adverse reactions. Examples include the reduced effectiveness of thyroid medication ‘levothyroxine’ if taken alongside iron supplements, or the vitamin K in leafy green vegetables inhibiting the anti-blood-clotting action of blood thinning drugs.

3- Drug-Condition Interactions:

Pre-existing medical conditions also have the potential to cause negative reactions to certain drugs being taken for a relatively new condition, like taking nasal decongestants for sinus treatment in patients with hypertension can elevate blood pressure to dangerous levels. Moreover, reduced metabolization with age, or kidney and liver disease can also prolong a drug’s stay in the body, causing adverse health effects.

Health Risks:

The effects of drug interactions can produce various moderate to major effects:

  • Changes in blood pressure
  • Ruptured Achilles tendon
  • Rapid heartbeat
  • Drowsiness
  • Bleeding
  • Flushing
  • Diarrhea
  • Coma
  • Death

Affecting Factors:

While most drug interactions are unpredictable, their likelihood increases with the presence of one or more of the following factors:

  • Age
  • Dosage
  • Genetics
  • Duration
  • Physiology
  • Underlying diseases
  • Lifestyle (diet, exercise)
  • Increased number of medications
  • Relative administration time between two substances (in which case interactions can be avoided if the two suspected drugs are taken at different times).

How To Avoid Them:

Most drug reactions can be avoided by adopting the following measures:

1- Always Read Drug Labels:

Remember to read those lengthy papers included in the package inserts of all medications for accurate information regarding a particular drug’s use, side-effects, drug-interaction precautions, active ingredients and possible allergens present in it.

If the information appears too complex, ask your doctor or pharmacist for a quick summation, as proper education is the first step in avoiding drug interactions. Moreover, OTC drug labels continuously change with the addition of new information, so always read the labels, even if you’ve been taking the same medication for years.

2- Discuss With Your Doctor:

Present your doctor(s) with a list of all currently-used medications, including prescription and OTC drugs, dietary and herbal supplements, vitamins, current, and past medical conditions, and allergies to aid them in the prescription process. Also discuss your family history, eating habits, current diet plans and whether or not you smoke, or are pregnant or breastfeeding, as it can affect the prescription and medications’ effectiveness.

3- Know How To Take Them:

Ask your doctor or pharmacist whether or not to take your medication with food, as it might aid or hinder the absorption of certain drugs. For instance, the antibiotic tetracycline shouldn’t be taken with dairy products as the calcium content can negatively affect its absorption.

4- Measure Accurately:

In case of liquid medicines, use marked cups or droppers (which usually come with the medication), making sure not to use multiple medicines in the same cup to avoid accidental reactions. Moreover, opt for measuring spoons over household spoons due to multiple size variations, making overdosing or under-dosing highly likely.

5- Avoid Medicinal Mutilation:

Chewing, crushing, breaking and mixing capsules or tablets with a liquid (juice, tea, etc.) unless instructed by the doctor might reduce their effectiveness. Moreover, breaking down certain long-acting medications before ingestion can accelerate their absorption process and cause adverse effects.

6- Don’t Share:

Medicines, particularly those for serious conditions like diabetes and heart disease, are prescribed according to an individual’s health and medical history, so avoid using someone else’s medication even if you have the same condition, and vice versa.

According to a study conducted by a hospital in Hyderabad, Pakistan, 24% of the collected 250 prescriptions contained reactive drugs; and this is only the number of prescriptions from one hospital. Such statistics make drug-interaction awareness necessary among consumers, doctors and pharmacists alike.

If you are concerned about your current prescriptions, we recommend you to consult a physician and seek advice.

At oladoc, you can find a General Physician in Lahore, Karachi, and Islamabad and get a confirmed appointment. Moreover, you can also get an appointment by calling our helpline: 042-3890-0939.

Disclaimer: The contents of this article are intended to raise awareness about common health issues and should not be viewed as sound medical advice for your specific condition. You should always consult with a licensed medical practitioner prior to following any suggestions outlined in this article or adopting any treatment protocol based on the contents of this article.

Dr. Munir Hussain - Author Dr. Munir Hussain Shah is a Nutritionist practicing in Multan. Dr. Munir Hussain Shah has the following degrees: MBBS, PGD (ALOU) and has 32 years of experience. You can book an appointment with Dr. Munir Hussain Shah by calling us or using the 'book appointment' button.
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