What happens after taking deworming syrup?: A Comprehensive Guide

October 8, 2025 •

5 min read

According to the World Health Organization (WHO), regular deworming is recommended in areas where parasitic worms are prevalent, and understanding what happens after taking deworming syrup is crucial for managing expectations and monitoring the treatment's effectiveness. This guide provides a detailed look at the effects and side effects of deworming medication.

Quick Summary

The medication works to eliminate intestinal parasites, often resulting in mild, temporary side effects such as nausea or abdominal pain, with the worms being expelled in stool over a few days. You will learn about the mechanism of action, the timeline of effects, and what to monitor after treatment.

Key Points

Mechanism: Deworming syrup works by either starving the intestinal parasites of glucose or paralyzing them, leading to their death and expulsion from the body.
Timing: The medication starts working within hours, and the worms are typically expelled over the next few days.
Side Effects: Mild and temporary side effects like nausea, abdominal pain, and headache are common, especially with heavy infections.
Expulsion: Modern deworming medicines often dissolve the worms, so it is unlikely you will see visible worms in the stool.
Follow-Up: A second dose may be required after two weeks to kill any newly hatched worms, as the initial dose may not kill the eggs.
When to See a Doctor: Seek medical attention for severe allergic reactions, signs of blood or liver problems, or if symptoms persist beyond the treatment period.
Prevention: Maintain good personal hygiene and sanitation to prevent re-infection after the treatment is complete.

The Mechanism of Deworming Syrup

Deworming syrups, also known as anthelmintics, are designed to eliminate parasitic worms from the body, primarily in the intestines. Common active ingredients in these medications include mebendazole and albendazole, which work in two primary ways to kill the parasites.

Starvation: Medications like mebendazole and albendazole work by blocking the worms' ability to absorb glucose (sugar), which is their main energy source. Deprived of energy, the worms lose vitality and eventually die. This is the most common mechanism for many intestinal worm infections.
Paralysis: Other anthelmintics, such as pyrantel, work by paralyzing the worms. This causes the worms to lose their grip on the intestinal wall, allowing them to be dislodged and passed from the body in the stool.

It is important to note that most modern deworming medications effectively target adult worms and larvae but do not kill the worm eggs. This is why a repeat dose is often recommended after two weeks to prevent re-infection as the remaining eggs hatch.

The Timeline of Effects and Expulsion

After taking deworming syrup, the medication begins to work relatively quickly, but the full effects take some time to become noticeable. The exact timeline can vary depending on the type of worm, the severity of the infection, and the medication used.

Initial Action (Hours to Days): The medication is absorbed and begins affecting the worms immediately. Symptoms of a heavy infestation, such as abdominal pain, may start to subside within a few days.
Bowel Movement (Hours to Days): Many people may feel the urge to have a bowel movement within a couple of hours, but it is also normal for this to take up to 2–3 days. Modern deworming medicines often dissolve the worms, so it's less likely you will see them in the stool compared to older treatments. Instead, you may just notice an improvement in digestive symptoms.
Complete Treatment: A full course of treatment, which can be a single dose or a regimen over several days, is necessary to clear the infection. As mentioned, a repeat dose is often needed two weeks later to catch any newly hatched worms.

Common and Severe Side Effects

While deworming syrup is generally well-tolerated, especially when taken with food, some side effects are possible. These are typically mild and transient, often more pronounced in individuals with heavy worm infestations.

Common (Mild) Side Effects

Gastrointestinal Issues: Nausea, vomiting, diarrhea, abdominal pain, and gas are common as the body eliminates the parasites.
Headaches and Dizziness: Some individuals may experience mild headaches or feelings of dizziness after taking the medication.
Fatigue: Unusual weakness or tiredness can occur.
Itching and Rash: Mild, transient itching or skin rashes can occur, sometimes indicating a mild allergic reaction.

Severe (Rare) Side Effects

Severe Allergic Reactions: Symptoms like severe rash, itching, hives, or swelling of the face, lips, or tongue require immediate medical attention.
Blood Disorders: In rare cases, usually with prolonged or high-dose use, blood disorders like low white blood cell count (neutropenia) can occur. Symptoms include fever, frequent infections, unusual tiredness, and easy bruising.
Liver Problems: Signs of serious liver issues, such as dark urine, pale stools, yellowing of the skin or eyes, loss of appetite, and persistent stomach pain, must be reported to a doctor immediately.
Seizures: While extremely rare, seizures have been reported, particularly when treating infections like neurocysticercosis with drugs like albendazole.

Comparison of Common and Severe Side Effects


Characteristic	Common (Mild) Side Effects	Severe (Rare) Side Effects
Onset	Occurs shortly after taking medication, especially with heavy infestation.	Can occur anytime, sometimes with prolonged or high-dose use.
Symptoms	Nausea, abdominal pain, diarrhea, headache, fatigue, mild rash.	Severe rash, hives, swelling, fever, chills, unusual bleeding, dark urine, pale stools, yellow skin/eyes.
Duration	Usually resolve on their own within 1-2 days.	Persist, worsen, or appear suddenly; require medical intervention.
Action Required	Rest, stay hydrated, take with food to minimize discomfort.	Stop medication immediately and seek emergency medical care.

Signs of Effective Treatment

Monitoring your body's response is key to confirming that the deworming syrup has worked. Beyond the expulsion of worms, other signs indicate successful treatment.

Resolution of Original Symptoms: Over the next few days to weeks, you should notice the primary symptoms of the worm infection, such as an itchy anus, abdominal discomfort, and loss of appetite, begin to disappear.
Improved Well-being: For children, in particular, successful deworming can lead to improved appetite, better nutrient absorption, and increased energy levels. Long-term benefits, such as improved growth and reduced anemia, have been observed in studies.
Repeat Stool Test (If Necessary): In some cases, a follow-up stool test might be performed several weeks after treatment to confirm the infection is completely gone.

Important Considerations and When to Consult a Doctor

While deworming syrup is a safe and effective treatment for many, it is not suitable for everyone. Certain individuals should avoid deworming medications or use them only under strict medical supervision.

Pregnant or Breastfeeding Women: Most deworming medications are not recommended, especially during the first trimester of pregnancy.
Children Under a Certain Age: Albendazole and mebendazole are typically not recommended for children under 12 months or 24 months, respectively, without a doctor's guidance.
People with Pre-existing Conditions: Individuals with liver disease, kidney failure, or a history of bone marrow issues should consult a doctor before treatment.

Consult your doctor immediately if you experience severe side effects or if your symptoms do not improve after the treatment course. It's also important to follow proper hygiene practices, such as washing hands thoroughly and frequently, to prevent re-infection, as the medication does not kill all worm eggs. For comprehensive information on deworming medications, you can consult reliable sources like the NHS website on Mebendazole.

Conclusion

After taking deworming syrup, you can expect the medication to act on the intestinal parasites within hours, with the dead worms being expelled over the next few days through bowel movements. Mild, temporary side effects are common, but they often resolve on their own. Successful treatment will lead to the gradual resolution of the infection's original symptoms. To ensure complete eradication and prevent re-infection, it is crucial to follow the prescribed dosage, including any repeat treatments, and maintain excellent hygiene. If severe side effects occur or symptoms persist, seeking medical advice is the correct course of action.

Frequently Asked Questions

With modern deworming syrups, it is unlikely you will see visible worms in your stool. The medication often dissolves the parasites, which are then expelled in the feces over a period of a few hours to several days.

The most common side effects are mild and temporary, and may include nausea, abdominal pain, diarrhea, headaches, and fatigue, especially if you have a heavy worm infestation.

While modern deworming medication can be taken with or without food, taking it with a meal, especially one containing some fat, can improve its absorption and may help minimize mild stomach upset.

Many deworming medications do not kill the worm eggs, only the adult worms and larvae. A second dose, typically taken two weeks after the first, is often necessary to eliminate any worms that have hatched in the meantime.

You should contact a doctor if you experience severe symptoms like fever, chills, severe rash, unusual bleeding, dark urine, or yellowing of the skin or eyes. Also, if mild side effects persist for more than a couple of days or your initial symptoms do not improve, it is best to seek medical advice.

To prevent re-infection, practice good personal hygiene by washing your hands frequently, especially before eating and after using the toilet. It is also important to maintain a clean living environment and ensure food and water are clean.

Deworming medication should only be administered to children under the guidance of a healthcare professional. Mebendazole and albendazole are often recommended for children over 12 months or 24 months, depending on the specific medication and context.