Does Trisul make you drowsy? Exploring the Link Between the Antibiotic and Fatigue

October 9, 2025 •

3 min read

According to prescribing information for its active ingredients, fatigue is a listed side effect of the antibiotic combination in Trisul, though it is not always a common occurrence. So, does Trisul make you drowsy? It is possible, but other factors, like the underlying infection, can also be a cause of tiredness.

Quick Summary

The antibiotic Trisul (trimethoprim/sulfamethoxazole) can potentially cause drowsiness or fatigue, though this is not a universal side effect. The infection being treated, dehydration, and high dosage can influence the presence and severity of symptoms.

Key Points

Drowsiness is a Possible Side Effect: The antibiotic combination in Trisul can cause fatigue or tiredness, though it is not a universally experienced side effect.
Underlying Infection Can Also Cause Tiredness: The fatigue experienced while taking Trisul may be a symptom of the infection itself, not just the medication.
Stay Hydrated and Rest: Managing fatigue involves getting plenty of rest and drinking fluids, as dehydration can worsen tiredness.
Severe Drowsiness May Indicate Overdose: Extreme drowsiness or confusion could be a symptom of an overdose and requires immediate medical attention.
Consult Your Healthcare Provider: If drowsiness persists or becomes severe, speak to a doctor or pharmacist to determine the best course of action, which may include timing adjustments or monitoring.
Avoid Alcohol and Driving: Avoid consuming alcohol with Trisul and refrain from driving or operating heavy machinery until you know how the medication affects you, as it can cause dizziness.

What is Trisul?

Trisul is a brand name for an antibiotic containing the active ingredients trimethoprim and sulfamethoxazole, also known as co-trimoxazole. This powerful combination is used to treat a wide range of bacterial infections, such as urinary tract infections, bronchitis, and traveler's diarrhea. The two components work synergistically to block consecutive steps in the bacterial synthesis of nucleic acids and proteins, preventing bacterial replication. Because it is a powerful antibiotic, Trisul can have a number of side effects, including the potential for drowsiness or fatigue.

The Connection Between Trisul and Drowsiness

While some medications are well-known for causing sedation, the link between Trisul and drowsiness is less clear-cut. For some individuals, feeling tired or fatigued while taking Trisul can be a direct side effect of the medication. In other cases, however, the fatigue may be caused by the body's response to the infection itself, rather than the medication. When fighting an illness, the body's immune system works overtime, which can lead to a general feeling of tiredness or weakness. Dehydration, which can occur during an infection, can also contribute to fatigue.

There are also scenarios where drowsiness or fatigue can signal a more serious issue. In cases of overdose, severe drowsiness is a reported symptom. If you experience extreme fatigue, dizziness, or confusion, especially alongside other severe symptoms, it is important to seek immediate medical attention.

Other Notable Side Effects

Beyond fatigue, Trisul has a list of other potential side effects. These can vary in severity and frequency among different individuals. Common side effects often include:

Nausea and vomiting
Diarrhea
Loss of appetite
Headache
Dizziness
Skin rashes or increased sensitivity to sunlight

Less common but more serious side effects may include severe skin reactions (like Stevens-Johnson syndrome), blood disorders, liver damage, or electrolyte imbalances. It is crucial to monitor for any unusual or worsening symptoms and to contact a healthcare provider immediately if they occur.

Managing Potential Drowsiness from Trisul

If you find yourself feeling drowsy or fatigued while taking Trisul, there are several steps you can take to manage the effect. First, prioritize rest to allow your body to recover from the infection. Taking short breaks throughout the day can also help conserve energy. It is also essential to stay well-hydrated, as dehydration can exacerbate feelings of tiredness. In some instances, your doctor or pharmacist may suggest taking the medication at a different time, such as in the evening, to minimize daytime sleepiness. Never adjust your dose or stop taking the medication prematurely, as this can lead to antibiotic resistance or a return of the infection. Always consult your healthcare provider before making any changes to your treatment plan.

Comparing Side Effects: Trisul vs. Other Antibiotics

Many antibiotics can cause fatigue, but the specific profile of side effects can vary. Here is a general comparison of potential side effects, including drowsiness, for Trisul and other common antibiotics.


Side Effect	Trisul (Trimethoprim/Sulfamethoxazole)	Penicillin-based Antibiotics (e.g., Amoxicillin)	Fluoroquinolones (e.g., Ciprofloxacin)
Drowsiness/Fatigue	Yes, possible, though severity varies; can be related to infection	Less common; fatigue is sometimes reported but not a primary side effect	Yes, some patients report fatigue or lethargy; can also cause insomnia
Gastrointestinal	Common (Nausea, vomiting, diarrhea, appetite loss)	Common (Nausea, vomiting, diarrhea)	Common (Nausea, diarrhea, stomach pain)
Skin Reactions	Common (Rash, sun sensitivity); serious reactions possible	Common (Rash); serious allergic reactions possible	Possible (Rash, sun sensitivity)
Neurological	Dizziness, headache, potential for severe effects	Generally minimal, though headaches can occur	Can cause dizziness, headache, confusion; rare but serious effects like nerve damage

Conclusion: Consult Your Doctor About Trisul

The question of whether Trisul makes you drowsy does not have a simple yes or no answer, as it can vary by individual and circumstances. While drowsiness and fatigue are documented side effects of the trimethoprim/sulfamethoxazole combination, these feelings can also be a result of the underlying infection, dehydration, or other factors. The most important takeaway is to be aware of the potential for this side effect and to communicate any significant symptoms with your healthcare provider. If you experience persistent or extreme tiredness, dizziness, or any severe side effects, it is crucial to seek professional medical advice. For more detailed clinical information, you can consult the drug's package insert available on Drugs.com.

Frequently Asked Questions

The prevalence of drowsiness or fatigue from Trisul is not well-documented, but it is a known side effect. For some, tiredness can be mild, while others may not experience it at all. It is also often difficult to separate medication side effects from fatigue caused by the illness itself.

Trisul can cause dizziness or drowsiness in some individuals. It is recommended to understand how the medication affects you before driving or operating heavy machinery. If you feel excessively sleepy or dizzy, you should refrain from driving.

First, ensure you are getting adequate rest and staying well-hydrated. You can also speak with your doctor or pharmacist about the possibility of taking your dose in the evening to reduce daytime sleepiness. Do not stop taking the medication without consulting a professional.

Yes, alcohol consumption should be avoided while taking Trisul, as it can increase drowsiness and may interfere with your body’s ability to fight the infection.

Trisul contains a combination of two active antibiotics: trimethoprim and sulfamethoxazole, also known as co-trimoxazole.

Yes, it is possible. Your body uses a lot of energy to fight off an infection, which can lead to a general feeling of fatigue and weakness. It's often a combination of the body's natural response and the medication's effects.

You should contact your doctor if the drowsiness is severe, persistent, or accompanied by other concerning symptoms such as severe dizziness, confusion, or mental/mood changes. Extreme drowsiness can be a sign of an overdose.