Bactrim and Alcohol

Estimated reading time: 34 minute(s)

Antibiotics form a significant part of life today, with millions of people using them every day to combat infections. Among the hundreds of antibiotics currently known to humans, Bactrim is a strong contender with powerful germ-killing properties. Combining trimethoprim and sulfamethoxazole, doctors often prescribe this synthetic antibacterial combination for infections of the windpipe, ear, and urinary tract. While most people can tolerate the antibiotic well, some may experience unwanted side effects which may affect their quality of life. These side effects are more prominent in specific categories, such as people mixing it with alcohol.

According to evidence, up to 10 percent of people who combine Bactrim with alcohol report experiencing adverse reactions. Additional studies have shown that people who use both substances concurrently are also at a much higher risk of developing skin reactions, liver damage, and gastrointestinal issues. For this reason, experts strongly advise against using Bactrim and alcohol together and educating everyone on the possible interactions that may occur.

According to recent studies, approximately 8-10% of those taking Bactrim DS reported adverse reactions after consuming alcohol. Additionally, studies show that those who take Bactrim DS and drink alcohol concurrently have a higher risk of developing gastrointestinal problems, skin reactions, and liver damage. For this reason, it is strongly advised to avoid alcohol consumption while taking Bactrim DS.

An Overview of Bactrim

Bactrim belongs to the category of antibiotics that combines two active ingredients: Trimethoprim and sulfamethoxazole. This manmade antibacterial combination is often available in double-strength (DS) tablets, each containing 160 mg of trimethoprim and 800 mg of sulfamethoxazole. On the other hand, the regular tablets have 400 mg of sulfamethoxazole and 80 mg of trimethoprim.

The primary indications of using Bactrim include the following types of bacterial infections:[1]

  • Bronchitis
  • Middle ear infections
  • Urinary tract infections
  • Bacillary dysentery
  • Traveler’s diarrhea
  • Pneumocystis jiroveci pneumonia

Bactrim and Alcohol Interaction: What to Expect?

When a person combines sulfamethoxazole and alcohol, they may be at risk of a side effect known as a disulfiram reaction.[2] This reaction occurs as Bactrim inhibits acetaldehyde dehydrogenase, a natural enzyme found in the liver that breaks down and metabolizes alcohol. When this enzyme becomes less active, alcohol starts building up in the body, leading to toxicity and a reaction characterized by the following symptoms:

  • Extreme flushing
  • Low blood pressure
  • Increased heart rate

The disulfiram reaction that takes place between Bactrim and alcohol still remains controversial as experts do not have enough data to support that it occurs when a person uses Bactrim in prescribed amounts with moderate alcohol consumption. The reaction is also more prevalent with other drugs, such as metronidazole, rather than Bactrim. Nevertheless, people have reported experiencing it after using Bactrim and alcohol; hence, it is imperative to remember it. The potential disulfiram reaction triggered by mixing Bactrim and alcohol can also increase the likelihood of experiencing gastrointestinal issues, such as severe nausea.

Why Avoid Drinking Alcohol While Taking Bactrim?

We have been hearing for a long time not to drink while taking antibiotics, such as Bactrim. According to experts, the reason behind avoiding this combination are multiple, and even though some of them require further research and workup, it is best to keep away from risk as much as possible.

Impact on Effectiveness

Alcohol does not carry the potential to interfere with how antibiotics work to destroy bacteria. However, theoretical concerns suggest that using it while completing an antibiotic course can make the latter less effective. In most cases, the liver responds to heavy alcohol consumption by increasing the synthesis of certain enzymes. Sometimes, these enzymes are also the ones that act on Bactrim and break it down. Hence, when a person takes this antibiotic while drinking alcohol, the body may break it down and eliminate it more quickly than usual, not giving it enough time to kill bacteria and trigger recovery.[3]

While scientists are still not sure if drinking while taking antibiotics can reduce the latter’s efficacy, it is still a good idea to avoid combining them both as long as we get definitive answers. The risk is still there for people who consume a drink or two per day, though it may be minimal. For regular drinkers, the risk can be considerably higher.

Side Effects

Another concern that experts may have for people combining alcohol with an antibiotic such as Bactrim is the increased risk of side effects. For instance, antibiotics on their own can cause many potential side effects, like nausea and stomach irritation. These side effects may increase in severity in people who have too much to drink. Other adversities related to the combination may include headaches, dizziness, and more.

When it comes to the side effects of combining Bactrim and alcohol, the liver is an important consideration. Antibiotics like Bactrim can put excessive strain on the organ, triggering damage, especially in people with co-existing liver issues. Since drinking on its own also damages the heart, it makes sense to avoid combining antibiotics with alcohol. Another reason to avoid the combination is its potential to depress the central nervous system. Additionally, the disulfiram-like reaction described above is one of the most common risks in people drinking alcohol while taking Bactrim, leading to symptoms like facial flushing, dizziness, sweating, and nausea. Combining the two substances can very rarely trigger severe symptoms, such as heart attack or very low blood pressure.

Impact on Healing

Using alcohol can interfere with the body’s ability to heal and recover from underlying illness. For instance, alcohol can make the body dehydrated and interfere with sleep.[4] Both issues can considerably slow down healing with time. Experts are still trying to understand the different ways in which alcohol affects the immune system. So far, it is clear that drinking heavily every day can exert all kinds of adverse effects on the immune system, weakening it and leaving the body undefended. However, these effects may not be so prominent in people who drink lightly or occasionally. 

How Long After Taking Bactrim Can I Drink Alcohol?

Since many people have reported experiencing disulfiram reactions after combining Bactrim with alcohol, it is critical to be cautious and avoid taking them together. But many people may raise the question regarding the amount of time they need to space out both substances to avoid any side effects. To answer these questions, remember that the body quickly absorbs Bactrim when taken through the mouth. The peak concentration of the drug is quickly achieved within one to four hours following the last dose.

In general, it would be a good idea to avoid taking alcohol when the body contains Bactrim in peak concentrations. Hence, most experts advise limiting alcohol for at least 4 hours after taking the antibiotic. These four hours are the time when the user is at the highest risk of acquiring vomiting, nausea, and other side effects the combination may bring.

It is also essential to consider how long Bactrim will last in the body. The antibiotic is known to have a half-life of 8 to 12 hours. The term ‘half-life’ describes the time it takes the body to reduce a drug’s concentration by half. What this means is it will take at least a few days for the body to metabolize and kick out Bactrim from the system completely. Keeping this in mind, an ideal practice would be to not drink alcohol for up to three days following the last dose of Bactrim. Successful abstinence for this time period can significantly reduce the risk of an unwanted reaction.

Warning Signs of Polysubstance Addiction

While most people find the side effects of mixing alcohol with Bactrim uncomfortable and unpleasant, others may start enjoying them and pursue taking the combination habitually to experience them repeatedly. This routine mixing can easily cause a person to develop a substance use disorder, possibly developing into polysubstance abuse if both substances are abused together. [5]

One of the earliest signs that a person is addicted to mixing Bactrim and alcohol is that they start experiencing intense cravings for the combination. If such people take one of the substances, they find themselves craving the other, indicating the earliest signs of addiction-forming and dependence. Another classic sign that addiction to both Bactrim and alcohol is underway is experiencing unwanted withdrawal symptoms when a person skips one or both substances or significantly reduces their dosage. These withdrawal effects occur as the body struggles to deal with the lack of Bactrim and alcohol that it has become dependent on for operating normally. The earliest signs of such a withdrawal may include nausea, irritability, tremors, headaches, and more.

Lastly, many people addicted to the combination of Bactrim and alcohol may show increased efforts to have both substances on hand to prevent withdrawals. This may include changing social circles to include people who can help them source these substances more easily. If you or someone you know has been showing the classic signs mentioned above, it might be worth trying to seek help from a professional rehab. These rehabilitation centers provide supervised care and treatment to help patients recover from polysubstance use while encouraging them to maintain a sober life.


Can you take Bactrim and alcohol together?

Experts advise not to use Bactrim and alcohol at the same time as the combination may lead to side effects. In addition, the combination can also reduce the efficacy of Bactrim, making the body struggle hard to fight the infection and even possibly lead to unwanted complications.

What happens if you mix Bactrim and alcohol?

When a person combines bacterium with alcohol, the duo increases the risk of certain side effects, such as nausea, dizziness, vomiting, increased heart rate, and headaches. The combination may also increase the severity of the pre-existing side effects from Bactrim; hence, it is best to avoid them.

What are the alcohol and Bactrim death statistics?

Unfortunately, there is very limited research exploring the risk of mortality related to the combined use of Bactrim and alcohol. It is imperative to understand that the combination comes with risks, such as reduced antibiotic efficacy. Moreover, alcohol also exacerbates the side effects related to Bactrim, including stomach ache, fatigue, headaches, vomiting, and nausea. Hence, experts advise holding alcohol intake till the time they finish their antibiotic course.

How long does Bactrim stay in your system?

According to experts, Bactrim still remains inside the body in detectable amounts 24 hours following the last dose.

Does alcohol make Bactrim less effective?

While alcohol consumption does not directly target how effectively an antibiotic work, it can make the body struggle harder to recover from whatever illness or infection it is battling. Additionally, people undergoing an active session of sickness require proper hydration to recover fully. Drinking alcohol can prevent this from happening as it dehydrates the body, making recovery difficult. Moreover, both alcohol and Bactrim are processed by the liver before they can break down and exit from the body. When the liver is already busy fighting an infection, adding alcohol to the picture may cause it to overwork, sometimes even triggering liver toxicity.

What if I accidentally had a drink after taking Bactrim?

If you unknowingly had a drink after taking Bactrim, do not panic. It is very unlikely that a single drink or two will trigger severe side effects. Keep monitoring your body and watch out for any unusual symptoms. Mild symptoms, like stomach ache and nausea, may settle on their own with time. However, if you develop something severe or unusual, do not hesitate to contact a doctor.


1 Kemnic TR, Coleman M. Trimethoprim Sulfamethoxazole. [Updated 2022 Nov 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from:

2 Mergenhagen KA, Wattengel BA, Skelly MK, Clark CM, Russo TA. Fact versus Fiction: a Review of the Evidence behind Alcohol and Antibiotic Interactions. Antimicrob Agents Chemother. 2020 Feb 21;64(3):e02167-19. doi: 10.1128/AAC.02167-19. PMID: 31871085; PMCID: PMC7038249.

3 Weathermon R, Crabb DW. Alcohol and medication interactions. Alcohol Res Health. 1999;23(1):40-54. PMID: 10890797; PMCID: PMC6761694.

4 ROBERTS KE. Mechanism of Dehydration Following Alcohol Ingestion. Arch Intern Med. 1963;112(2):154–157. doi:10.1001/archinte.1963.03860020052002

5 Crummy EA, O’Neal TJ, Baskin BM, Ferguson SM. One Is Not Enough: Understanding and Modeling Polysubstance Use. Front Neurosci. 2020 Jun 16;14:569. doi: 10.3389/fnins.2020.00569. PMID: 32612502; PMCID: PMC7309369.

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