Drug interaction: what are the risks and how to avoid?

A lot of people hear about drug interactions and even have a sense of what it is about. However, not everyone knows that there are several possible relationships between medications – cutting effect, increasing or decreasing, for example.

In addition, the interaction does not always occur between two remedies, they can be between a substance, such as tobacco, or even with food.

Therefore, it is always worth reading the package insert and clearing doubts in the medical or pharmaceutical consultation! Do you want to know more about this subject? Then check it out:


What is drug interaction?

The National Health Surveillance Agency (ANVISA) defines drug interaction as “a clinical event in which the effect of a drug is altered by the presence of another drug, food, drink or some chemical agent”.

Quite simply, this occurs when a drug has its effects increased, reduced or canceled because of some factor.

The most dangerous outcomes are usually associated with the toxicity of one drug – that is, when one substance increases the toxic potential of another. However, reducing the effect of a drug can also be quite dangerous, as it may not have the necessary effect and, in extreme cases, compromise the health of patients.

In fact, it is not only between remedies that the interaction can occur. Attention should be paid to the joint use of:

 is, factors that can determine whether or not it will happen.

In addition, it is very difficult to predict exactly the effects and reactions when someone uses two substances that have the potential to interact with each other. Thus, even a known interaction may not affect everyone in the same way.

In general, the most frequent occurrences do not involve great risks, and often, patients and professionals end up even knowing that there was an interaction, as it does not generate evident signs or symptoms.

Can drug interaction be beneficial?

Although almost always associated with a bad thing, some cases of interaction can be usefully used. Among the possibilities is the increase in the action of a substance or the elimination of adverse effects of it.

An example of this is the consumption of antibiotics with meals. Since medications of this type tend to cause reactions such as heartburn , excessive gas , diarrhea and nausea, eating with food reduces adverse effects.

Or, for example, the combined administration of antihypertensives and diuretics causes the latter to increase the effect of the former.

What are the risks of drug interaction?

Most of the time, drug interactions are not serious. Many people do not even discover that they mix substances, foods or medications capable of interacting with each other.

However, they can still be dangerous.

Although many people think that the drug interaction is only serious when the substance has a toxic action in the body, the reduction or cancellation of the effect can also be serious.

For example, using antibiotics in conjunction with antacids reduces the effect of the former – which means that, even though there are no serious adverse effects from the interaction, the infectious agents are not combated, which can aggravate the person’s clinical condition.

In addition, some combinations can result in serious conditions, such as anti-inflammatory drugs combined with anticoagulants. In that case, patients may suffer from bleeding.

Is alcoholic medicine dangerous?

Overall, yes. Each drug will interact in a different way – its effect may be diminished, increased or canceled, for example.

As alcohol and many medications are metabolized by the liver, this organ is one of those that can be compromised during mixing. In other words, alcohol and paracetamol is a prohibited combination due to the risks of medicated hepatitis.

Know a little about the risks of these combinations:

  • Alcohol and dipyrone: can increase the effects of alcoholic beverages;
  • Alcohol and acetylsalicylic acid: as acetylsalicylic acid irritates the stomach mucosa, there are risks of stomach bleeding;
  • Alcohol and antibiotics like Metronidazole; Trimethoprim-sulfamethoxazole, Tinidazole, Griseofulvin: can lead to intoxication of the organism, causing vomiting, palpitation, headache, pressure drop, difficulty breathing and even death);
  • Alcohol and antibiotics such as ketoconazole, nitrofurantoin, erythromycin, rifampicin and isoniazid: the drink can inhibit the action of the medication and / or lead to liver damage;
  • Alcohol and antidepressants: the effects of the medication can be reduced, in addition to increasing the sedative effects of the medication;
  • Alcohol and anxiolytics: sedative effects can be increased, leading to moderate to severe conditions, including coma and death;
  • Alcohol and anticonvulsants: adverse effects can be aggravated, with the risk of intoxication. In addition, the drug tends to be less effective against attacks of epilepsy.

What are the most common drug interactions?

In general, the possibility of drug interaction is higher for those people who use various medications or who usually self-medicate.

It is not difficult to observe cases among commonly used medications, such as paracetamol and dipyrone. And this is precisely because they are remedies considered to be without great dangers. However, not reading the package leaflet or not following medical instructions can result in serious conditions, such as damage to the stomach when mixing anti-inflammatory drugs with alcohol.

See some of these examples:

Between remedies

The most common drug interactions between drugs are:

  • Contraceptives have their effect diminished or canceled when taken with antibiotics;
  • Antibiotics can lose their effect if they are swallowed with antacids;
  • Vitamin K tends to decrease the response of oral anticoagulants;
  • Antacids decrease or delay the effect of anti-inflammatories;

With food

The most common drug interactions between drugs and food are:

  • Milk tends to cancel out the effect of Tetracyclines;
  • Anti-inflammatories should be taken with meals to avoid stomach irritation;
  • Antifungals are best absorbed when used in conjunction with fatty foods (such as fried foods);
  • Sugars and fats can hinder the action of antidiabetic drugs. The same goes for the mixture between salt and medicines to fight hypertension.

Ah, always choose to take the medication with the aid of mineral water, unless there is a medical recommendation for the medicine to be swallowed in another way.

This is because there are some drinks (including juices and teas) that can end up causing drug interactions or even causing stomach discomfort.

How to know if there is a risk of drug interaction?

Reading the package insert is the best way to find out if the drug you are taking may have any drug interactions with other drugs, substances or foods. It contains all the essential information for the conscious use of the medicine.

To find the drug interaction in the package insert, just look for the topic entitled “What should I know before taking this medication?”.

But we don’t always keep this very important piece of paper. At these times, the internet can be a good ally.

Sites such as Consulta Remédios and the electronic file of the National Health Surveillance Agency (ANVISA) make the task of consulting the package insert simpler.

But if you still have doubts, the best thing is to go to the nearest pharmacy and talk to a pharmacist.

How to avoid?

Some very simple precautions can be taken in order to avoid drug interactions and other health risks:

Talk to healthcare professionals

When consulting doctors or pharmacists, always advise about all medications you already use.

This list should also include substances for occasional use, such as chlorides, extracts, hormone or vitamin replacement capsules, etc.

As mentioned earlier, it is still possible for drug interactions to occur with other external factors, such as tobacco or alcohol. Therefore, the medical professional must be aware of these conditions.

Read the leaflet

As stated before, reading the package insert is one of the fundamental steps to avoid drug interactions.

There, it is possible to find information on medicines, substances and foods that interfere with the action.

Do not practice self-medication

In addition to being able to camouflage symptoms and postpone a correct diagnosis, self-medication can put patients’ health at risk.

The best way to avoid any damage or adverse event resulting from the use of medicines is to do so in a targeted manner. For this, consulting professionals in medicine and pharmacy is essential.

Drug interaction happens when a drug can have its effects altered due to other drugs, food, smoking and alcohol consumption.

Although it is beneficial in some cases, care must always be taken, since drug interactions can also reduce or cancel the effect of a drug, or cause further complications.

Not practicing self-medication, reading the package leaflet and seeking medical or pharmacological guidance are the best ways to avoid it.