Drugs and Alcohol

Drugs and Alcohol Vivian Pharmacy Article

The staff at Vivian Pharmacy are passionate about Pharmaceutical Care. Our mission is to provide our patients with the best pharmaceutical service by ensuring they are well supported in taking their medications effectively and safely.We have a team of clinically orientated pharmacists and pharmacy technicians who are always happy, in addition to medication supply, to answer drug questions, counsel patients and provide medication education. Here is the next article in our series on the complexities of safe and effective Pharmaceutical Care.

Words by Ger Jones, pharmacist

Mixing Alcohol With Medicines

Alcohol, from a pharmacological perspective, is most definitely considered a drug. It is actually a potent Central Nervous System depressant. On many of the drugs we dispense, it is common for us to add cautionary labels which advise limiting alcohol intake. Mixing alcohol with certain medications can cause nausea and vomiting, headaches, drowsiness, fainting, or loss of coordination. It also can put patients at risk for internal bleeding, heart problems, and difficulties in breathing. In addition to these dangers, alcohol can make some medications less effective or it may make the medication harmful to the body.

Examples of commonly used classes of prescription drugs associated with serious alcohol interactions include (but not limited to) some heart medications, nonsteroidal anti-inflammatory drugs, blood-thinning medications and sleep medications.

Also, as we age we develop more chronic diseases and there is a tendency for us to take more medications thus resulting in the potential for alcohol/drug interactions to go up. It is important to note also that the liver’s ability to metabolise alcohol and other drugs decreases with age.

Let us look in more detail at some drug/ alcohol interactions.

Opiates (Drugs such as morphine and codeine)

Mixing these drugs with alcohol may make patients feel drowsy and dizzy, as well as experience slowed or difficult breathing, impaired motor (movement) control, unusual behaviour, and problems with memory

Antianxiety agents (Benzodiazepines such as diazepam and clonazepam)

Again, mixing these drugs can make patients feel drowsy and dizzy, and increase the potential risk for overdose. As above, patients may experience slowed breathing, difficulty breathing, impaired motor control, unusual behaviour, and memory problems.


This is an antibiotic that’s used to treat certain types of bacterial and parasitic infections. It reacts badly with alcohol and may cause several unpleasant side effects, including throbbing in the head and neck, irregular heartbeat, rapid heartbeat, low blood pressure, sweating, nausea, and vomiting. Even a small amount of alcohol (e.g. 15 ml or one tablespoon) can trigger the effects. The interaction may last from 30 to 60 minutes to several hours, depending on the amount of alcohol consumed. We advise the avoidance of alcohol while taking metronidazole and for 3 days after the last dose.

It is interesting to look at this classic alcohol /drug interaction a little closer as it illustrates the importance the liver in drug therapy. In the liver, alcohol is converted to acetaldehyde, which is then broken down by the enzyme aldehyde dehydrogenase to a harmless derivative. It is thought that metronidazole stops this enzyme working and acetaldehyde builds up and causes unpleasant effects. As acetaldehyde is one of the major causes of the symptoms of a “hangover”, this produces immediate and severe negative reaction to alcohol intake.

So how to keep yourself safe:

• Do not drink alcohol if you are also taking medicine that can interact with it. Better safe than sorry.

• Our pharmacists can help you determine which medications interact harmfully with alcohol.


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