This site uses cookies.

The interaction between medications and ethanol (alcohol) - Dr Mark Burgin

09/08/23. Dr Mark Burgin discusses the legal implications of drug – alcohol interactions and how to recognise the common patterns that present in legal cases.

Lawyers are often encounter clients whose problems may have been worsened by their alcohol intake. This can be a claimant who suffered side effects from a drug prescribed by their doctor worsened by their use of alcohol. The defendant found to be over the limit days after their last alcohol intake. Sedation, anaesthesia or even surgical anaesthesia due to an interaction between alcohol and a prescribed medication. This article gives the lawyer a summary of the common interactions and their legal significance.

There are many issues such as impaired judgement and fluctuating capacity, failure to adhere to medication to avoid side effects, failure to consider alcohol as the cause of the symptoms or as a risk factor for side effects.

Several issues arise from these interactions, including impaired judgment, fluctuating capacity, failure to adhere to medication regimens to avoid side effects, and failure to consider alcohol as a potential cause or risk factor for symptoms. It is crucial for doctors to customize therapy for individuals with higher alcohol intakes and ensure robust monitoring and follow-up for these patients. Moreover, doctors may have a greater responsibility to evaluate whether the prescribed medication serves the patient's best interests when alcohol consumption is involved.

Although many problems can occur when a drug or the alcohol is stopped or started other problems can appear slowly during combined use. Many people who suffer from harm as a result of their alcohol usage could have that harm reduced or prevented by proper monitoring. The following examples demonstrate the varied and complex ways in which medication and alcohol can interact, leading to problems:

· Opiates: Ethanol has a sedative effect on the central nervous system, and when combined with opioids (e.g., oxycodone, codeine), it can enhance the sedative effects, leading to excessive drowsiness, respiratory depression, or even overdose. A doctor prescribing opiates for pain must warn the patient that the drug can cause drowsiness and further that alcohol may potentiate the effects of the drug.

· Antipsychotic medications: Ethanol can enhance the sedative effects of antipsychotic medications, such as haloperidol or risperidone. This combination can lead to excessive drowsiness, impaired coordination, and increased side effects. Many patients with psychosis self treat with alcohol as well, the dose of the antipsychotic medication must be started low to prevent risks to the patient.

· Anticonvulsant medications: Combining alcohol with anticonvulsant medications, such as phenytoin, valproate, lamotrigine or topiramate can lower the seizure threshold and increase the risk of seizures controlling seizures and induce enzymes which can reduce the effectiveness of a dose. When the patient stops drinking the drug levels and potency can both rise leading to sedation or even anaesthesia.

· Antidepressants: Ethanol can interfere with the effectiveness of some antidepressant medications, such as selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs). It can also worsen the side effects of these medications, such as drowsiness, dizziness, and impaired coordination and the withdrawal effects. Depressed patients will fear stopping alcohol and increase their intake to manage the agitation that they suffer.

· Antihistamines: Mixing alcohol with antihistamines, including over-the-counter medications for allergies, can cause increased drowsiness and impair cognitive function. Combining alcohol with sedating antihistamines, such as diphenhydramine or doxylamine, can increase drowsiness and impair cognitive function especially in the elderly. Doctors may not consider the ACh components of the medications which can combine to cause or worsen memory problems and mimic dementia. This has led to mental capacity issues and legal challenges when the patient regains capacity when the causes are removed.

· Muscle relaxants: Combining alcohol with muscle relaxants, such as carisoprodol or baclofen, can enhance the sedative effects and increase the risk of drowsiness, dizziness, and impaired coordination. It can also potentiate the muscle relaxant's impact, leading to excessive muscle relaxation. The onset of these effects can be sudden and overwhelming for instance during driving.

· Anticoagulants and Antiplatelet Agents: Alcohol can increase the risk of bleeding when combined with medications like warfarin, heparin, aspirin, or clopidogrel. It can interfere with the clotting process due to liver damage and increase the risk of bruising, bleeding, or haemorrhage. It is worth noting that alcohol can also increase the risk of bleeding when combined with newer oral anticoagulants, such as apixaban or rivaroxaban. Many patients who suffer head injuries with bleeds have been prescribed anticoagulants despite being known to have alcohol problems.

· Nonsteroidal Anti-Inflammatory Drugs (NSAIDs): Mixing alcohol with NSAIDs like Ibuprofen or Naproxen can increase the risk of gastrointestinal bleeding and stomach ulcers, as both alcohol and NSAIDs can irritate the stomach lining. They can also cause an enteropathy with profuse diarrhoea and patients should be warned of the risks. Co-prescription with a PPI to protect the stomach may be insufficient and where this combination is considered then close monitoring may be required.

· Inducers of liver enzymes: Certain drugs can induce the activity of liver enzymes, including those involved in alcohol metabolism. Examples of such drugs include phenobarbital, rifampicin, and some antiepileptic medications (e.g., phenytoin, carbamazepine). By increasing the activity of these enzymes, these drugs can enhance the metabolism of alcohol which risks depleting the chemicals used to protect the liver from damage from alcohol.

· Diabetes Medications: Ethanol can affect blood sugar levels and interfere with the action of medications used to manage diabetes, such as insulin or oral hypoglycaemic agents such as sulfonylureas (e.g., glipizide) and meglitinides (e.g., repaglinide). It can cause hypoglycaemia (low blood sugar) or hyperglycaemia (high blood sugar) and make it challenging to control blood glucose levels. There have been a number of automatism cases

· Antihypertensive medications: Alcohol can interact with antihypertensive medications, such as ACE inhibitors, beta-blockers, GTN or angiotensin receptor blockers (ARBs), leading to an exaggerated drop in blood pressure. This can cause symptoms like dizziness, light-headedness, or fainting.

· Antibiotics: While not all antibiotics have interactions with alcohol, certain antibiotics, such as metronidazole and some cephalosporins, can cause adverse reactions when combined with ethanol. These reactions may include nausea, vomiting, flushing, rapid heartbeat, and headache.

· Antifungal medications: Some antifungal medications, such as ketoconazole or fluconazole, can interact with alcohol. Combining these medications with ethanol can lead to increased side effects, including gastrointestinal symptoms, liver toxicity, or abnormal heart rhythms.

· Antiretroviral medications: Certain antiretroviral medications used to treat HIV, such as protease inhibitors or non-nucleoside reverse transcriptase inhibitors, can interact with alcohol and affect liver function.

· Acetaminophen (paracetamol): Consuming alcohol while taking acetaminophen can increase the risk of liver damage. Both alcohol and acetaminophen can individually cause liver toxicity, and their combined use can exacerbate this risk.

· Cimetidine: Cimetidine is a medication used to treat stomach ulcers and gastroesophageal reflux disease (GERD). It inhibits the enzyme alcohol dehydrogenase, which is responsible for breaking down alcohol in the body. As a result, cimetidine can slow down the metabolism of alcohol, leading to higher blood alcohol levels.

· Disulfiram: Disulfiram is a medication used in the treatment of alcohol dependence. It works by inhibiting the enzyme acetaldehyde dehydrogenase, which is responsible for the breakdown of acetaldehyde, a toxic by-product of alcohol metabolism. When disulfiram is taken in the presence of alcohol, it causes unpleasant symptoms such as nausea, vomiting, and headache, discouraging the consumption of alcohol.

· Statins: Statin medications used to lower cholesterol, such as atorvastatin or simvastatin, may have an increased risk of liver damage when combined with alcohol. A doctor may not think to reduce the dose of the statin when managing a patient chronic liver problems.

· Cancer medications: Some cancer/immune treatments, such as methotrexate or fluorouracil, can interact with alcohol and increase the risk of liver damage or other adverse effects. Often these treatments can be continued without proper monitoring.

· Herbal supplements: Alcohol can interact with certain herbal supplements, such as kava or valerian root, St John’s wort and potentiate their sedative effects.

In conclusion, the interaction between medications and ethanol (alcohol) is a significant concern that lawyers and healthcare professionals must consider when dealing with clients or patients. This article has provided a comprehensive summary of common medication-alcohol interactions and their legal significance.

One of the key issues highlighted is impaired judgment and fluctuating capacity resulting from alcohol consumption, which can exacerbate the side effects of prescribed medications. Patients may fail to adhere to medication regimens or their doctors may overlook alcohol as a potential cause of their symptoms or consider them to be risk factors for side effects. Therefore, it is crucial for doctors to tailor therapy for individuals with higher alcohol intakes and ensure robust monitoring and follow-up for these patients, similar to reasonable adjustments made for individuals with disabilities.

The article discusses various medication classes and their interactions with alcohol. Opiates, antipsychotic medications, anticonvulsants, antidepressants, antihistamines, muscle relaxants, anticoagulants, NSAIDs, inducers of liver enzymes, diabetes medications, antihypertensive medications, antibiotics, antifungal medications, antiretroviral medications, acetaminophen, cimetidine, disulfiram, statins, cancer medications, and herbal supplements are all identified as having potential interactions with alcohol.

These interactions can range from enhanced sedative effects, respiratory depression, overdose, impaired coordination, agitation, lowered seizure threshold, increased drowsiness and cognitive impairment, excessive muscle relaxation, increased risk of bleeding, gastrointestinal complications, liver damage, altered blood sugar levels, exaggerated drop in blood pressure, liver toxicity, abnormal heart rhythms, increased risk of liver damage, and potentiated sedative effects, among others.

It is essential for healthcare professionals to educate patients about these interactions, especially the effects of alcohol on medication efficacy and potential risks. Lawyers must also be aware of these interactions when representing clients whose problems may have been worsened by alcohol intake and medication use.

This article was written with assistance from the Bard Large Language model from Google and ChatGPT from Microsoft.

Doctor Mark Burgin, BM BCh (oxon) MRCGP is on the General Practitioner Specialist Register.

Dr. Burgin can be contacted on This email address is being protected from spambots. You need JavaScript enabled to view it. and 0845 331 3304 website

This is part of a series of articles by Dr. Mark Burgin. The opinions expressed in this article are the author's own, not those of Law Brief Publishing Ltd, and are not necessarily commensurate with general legal or medico-legal expert consensus of opinion and/or literature. Any medical content is not exhaustive but at a level for the non-medical reader to understand.

Image ©

All information on this site was believed to be correct by the relevant authors at the time of writing. All content is for information purposes only and is not intended as legal advice. No liability is accepted by either the publisher or the author(s) for any errors or omissions (whether negligent or not) that it may contain. 

The opinions expressed in the articles are the authors' own, not those of Law Brief Publishing Ltd, and are not necessarily commensurate with general legal or medico-legal expert consensus of opinion and/or literature. Any medical content is not exhaustive but at a level for the non-medical reader to understand. 

Professional advice should always be obtained before applying any information to particular circumstances.

Excerpts from judgments and statutes are Crown copyright. Any Crown Copyright material is reproduced with the permission of the Controller of OPSI and the Queen’s Printer for Scotland under the Open Government Licence.