In general, it is recommended to avoid alcohol consumption while taking Bactrim (sulfamethoxazole/trimethoprim) as there could negative effects, both known and unknown.

Among other things, consuming alcohol can:

  • Affect drug metabolism (e.g. increase or decrease in metabolizing enzyme activity) (1)
  • Increase the risk of liver toxicity with medication (2)
  • Increase the risk of side effects (e.g. nausea/vomiting/diarrhea) (3)
  • Decrease immune system function (4)

Alcohol With Bactrim

In regards to Bactrim with alcohol specifically, Bactrim can inhibit  acetaldehyde dehydrogenase, which is largely responsible for alcohol metabolism (5).

If acetaldehyde dehydrogenase is less active, alcohol toxicity can build up and can cause what is known as a disulfiram reaction (6). This reaction is characterized by:

  • Extreme flushing
  • Increased heart rate
  • Low blood pressure

This potential 'disulfiram reaction' between alcohol and Bactrim is controversial as there is little data to support that it occurs with normally prescribed amounts of Bactrim and reasonable alcohol consumption. The reaction is more associated with other drugs, like Flagyl (metronidazole) (7). Nevertheless, the reaction has been reported and must be considered.​

In addition to the potential 'disufiram reaction', mixing alcohol and Bactrim can increase the risk of nausea and other gastrointestinal effects. Small amounts of alcohol, such as the amounts contained in liquid medication themselves, prepared meals etc... are generally safe however and shouldn't cause any issues.

Liver Disease Precaution With Bactrim

If the potential disulfiram reaction wasn't bad enough, if you have impaired liver function or a known folate deficiency, Bactrim needs to be taken cautiously and should not be combined with alcohol. Chronic alcohol consumption can cause folate deficiency and Bactrim in addition could exacerbate this condition.

When Can You Drink Alcohol After Bactrim?

Since disulfiram reactions have been reported on the combination of Bactrim and alcohol, it would be prudent to take caution and avoid the combination. Let's examine the ideal spacing between the two to decrease the possibility of this interaction.

Bactrim is rapidly absorbed when taken by mouth with maximum concentrations occurring 1-4 hours after taking a dose (8).

If you want to avoid consuming alcohol while concentrations are at their highest, 4 hours seems to be that upper limit.  Therefore alcohol should be avoided at least 4 hours after taking Bactrim. This may help avoid any kind of nausea or vomiting the combination might bring about.

We also have to consider how long Bactrim lasts in the body.

Bactrim has a half-life of 8-12 hours (half-life refers to the time it takes your body to reduce the concentration of the drug by 50%) meaning it would take a few days at least for the entire drug to be metabolized and out of your system. If you want to avoid alcohol and Bactrim being in your system at the same time, wait at least 3 days. Waiting this period of time will greatly reduce the risk of any type of reaction.