From the Guidelines
Terbinafine and Bactrim (sulfamethoxazole-trimethoprim) can be taken together as there is no significant drug interaction between them. However, patients should be aware that both medications can occasionally cause liver problems, so concurrent use might theoretically increase this risk. When taking these medications together, it's essential to monitor for signs of liver issues such as unusual fatigue, abdominal pain, dark urine, or yellowing of the skin or eyes. Both medications can also sometimes cause skin reactions, so any new rash or itching should be reported to a healthcare provider promptly. Terbinafine is an antifungal medication typically used to treat fungal infections of the nails or skin, while Bactrim is an antibiotic combination used for various bacterial infections. The medications work through different mechanisms - terbinafine inhibits fungal cell membrane synthesis while Bactrim blocks bacterial folate synthesis - which is why they don't directly interfere with each other's actions. According to the British Association of Dermatologists' guidelines for the management of onychomycosis 2014 1, terbinafine has minimal drug–drug interactions, with the only potentially significant interaction being with drugs metabolized by the cytochrome P450 2D6 isoenzyme. However, Bactrim, which contains sulfamethoxazole, is known to inhibit the CYP2C9 isoenzyme, as reported in a study on drug interactions affecting oral anticoagulant use 1. Despite this, there is no direct evidence to suggest a significant interaction between terbinafine and Bactrim. Regular blood tests may be recommended during treatment to monitor liver function, especially if the medications will be taken together for an extended period.
Some key points to consider when taking these medications together include:
- Monitoring for signs of liver problems, such as unusual fatigue or abdominal pain
- Reporting any new skin reactions, such as rash or itching, to a healthcare provider promptly
- Understanding the different mechanisms of action for terbinafine and Bactrim
- Being aware of the potential for increased risk of liver problems due to concurrent use of both medications.
It's also important to note that the study on drug interactions affecting oral anticoagulant use 1 highlights the importance of monitoring for potential interactions between antibiotics, such as Bactrim, and other medications. However, in the case of terbinafine and Bactrim, the available evidence suggests that they can be taken together without significant interaction.
From the Research
Interactions of Terbinafine with Bactrim
There is no direct evidence of interactions between terbinafine and Bactrim in the provided studies. However, we can discuss the potential for interactions based on the properties of these drugs.
Potential for Interactions
- Terbinafine is an antifungal agent that can cause liver injury, as reported in studies 2, 3, 4.
- Bactrim is an antibiotic that can also affect liver function.
- The potential for a drug-drug interaction between terbinafine and Bactrim exists, as both drugs can affect liver function and may increase the risk of liver injury when used together.
Mechanism of Interactions
- Pharmacokinetic interactions may occur, where one drug affects the absorption, distribution, metabolism, or excretion of the other drug 5.
- Pharmacodynamic interactions may also occur, where the effects of one drug are enhanced or diminished by the other drug 5.
Monitoring and Precautions
- Patients taking terbinafine and Bactrim together should be monitored for signs of liver injury, such as increased liver enzymes or jaundice 2, 3.
- Healthcare providers should be aware of the potential for interactions and take steps to minimize the risk of adverse effects, such as adjusting drug doses or monitoring liver function tests 5.