Can Pinworm Medicine Make You Sick? Understanding the Side Effects

October 13, 2025 •

4 min read

Pinworm infection is the most common worm infection in the United States, with an estimated 40 million people infected [1.7.1]. While effective treatments are available, a common question is: can pinworm medicine make you sick? The answer is yes, but side effects are typically mild.

Quick Summary

Pinworm medications can cause side effects, though many people experience none or only minor ones. Common reactions include nausea, headache, and stomach cramps. This article details the side effects of common treatments and when to see a doctor.

Key Points

Mild Side Effects are Common: Many people have no side effects, but common ones include nausea, stomach cramps, diarrhea, and headache [1.3.1, 1.4.5].
Three Main Medications: The primary treatments are pyrantel pamoate (OTC), mebendazole (prescription), and albendazole (prescription) [1.7.3].
Gastrointestinal Issues are Frequent: The most commonly reported side effects across all pinworm medications are related to the digestive system [1.3.3, 1.4.1].
Serious Reactions are Rare: Severe side effects like allergic reactions, liver problems, or bone marrow suppression are rare but require immediate medical attention [1.9.2, 1.5.5].
Know When to Call a Doctor: Contact a doctor for persistent or severe symptoms, or for signs of a serious reaction like rash, fever, or swelling [1.2.1, 1.3.1].
Household Treatment is Key: To prevent reinfection, it is recommended that all household members be treated at the same time [1.4.2].
Hygiene is Crucial: Strict handwashing and regular cleaning of bedding and clothing help prevent the spread and reinfection of pinworms [1.8.4].

The Reality of Pinworm Treatment Side Effects

Pinworm infection, or enterobiasis, is a widespread and highly contagious condition, especially among school-aged children [1.7.3]. Treatment is crucial to eradicate the parasites and prevent reinfection within a household. The most common medications used are available both over-the-counter (OTC) and by prescription. While these drugs are generally considered safe and effective, they are not without potential side effects [1.6.4]. Many individuals who take pinworm medicine experience no adverse effects at all. When side effects do occur, they are most often mild and temporary, resolving on their own [1.4.5]. The most frequently reported issues are gastrointestinal in nature, such as nausea, stomach cramps, vomiting, and diarrhea [1.3.1]. Other common effects can include headache, dizziness, and drowsiness [1.3.2]. It is important to remember that a healthcare provider prescribes these medications when the benefit of eliminating the infection is greater than the risk of side effects [1.6.4].

Common Pinworm Medications and Their Side Effects

There are three primary medications used to treat pinworm infections: pyrantel pamoate, mebendazole, and albendazole. Each works differently to eliminate the worms and has a distinct side effect profile.

Pyrantel Pamoate (e.g., Reese's Pinworm Medicine, Pin-X)

This is the most common OTC treatment for pinworms. It works by paralyzing the worms, which are then passed from the body in the stool.

Common Side Effects: The most frequent side effects are gastrointestinal, including abdominal cramps or pain, nausea, vomiting, and diarrhea [1.2.1, 1.3.3]. Headache, dizziness, drowsiness, irritability, loss of appetite, and trouble sleeping can also occur [1.2.1].
Rare but Serious Side Effects: Though rare, a serious allergic reaction is possible. Symptoms include rash, severe dizziness, swelling of the face, tongue, or throat, and trouble breathing, which require immediate medical attention [1.2.3].

Mebendazole (e.g., Emverm, Vermox)

Mebendazole is a prescription medication that works by preventing the worms from absorbing sugar (glucose), which they need to survive.

Common Side Effects: Stomach pain occurs in more than 1 in 100 people [1.6.1]. Other common effects include abdominal discomfort, diarrhea, gas (flatulence), nausea, and vomiting [1.4.2, 1.4.5].
Rare but Serious Side Effects: Mebendazole can, in rare cases, lead to more severe issues like bone marrow suppression, which lowers blood cell counts and increases infection risk [1.9.2]. Serious skin reactions like Stevens-Johnson syndrome have been reported, especially when taken with metronidazole [1.4.4, 1.9.1]. Signs of a severe reaction include blistering or peeling skin, sores in the mouth, and fever [1.4.2].

Albendazole (e.g., Albenza)

This is another prescription anthelmintic. Like mebendazole, it interferes with the worms' ability to absorb nutrients.

Common Side Effects: Common side effects may include headache, nausea, vomiting, stomach pain, and temporary hair loss [1.5.4, 1.5.3].
Rare but Serious Side Effects: Albendazole can cause serious issues, including liver problems, bone marrow suppression (leading to a drop in white blood cells), and increased pressure in the brain [1.5.5, 1.5.2]. Patients with pre-existing liver conditions should use this medication with caution [1.5.2]. Symptoms like severe headache, vision changes, yellowing skin or eyes, dark urine, and unusual tiredness warrant immediate medical attention [1.5.4].

Comparison of Pinworm Medications


Medication	Type	Common Side Effects	Key Considerations
Pyrantel Pamoate	Over-the-counter	Nausea, vomiting, abdominal cramps, diarrhea, headache, dizziness [1.2.1]	Generally mild side effects. Should be used with caution in patients with liver disease [1.3.1].
Mebendazole	Prescription	Abdominal pain, diarrhea, gas, nausea, vomiting [1.4.2]	Do not take with metronidazole due to risk of severe skin reactions [1.4.4]. Rare risk of lowering white blood cell count [1.4.4].
Albendazole	Prescription	Headache, nausea, stomach pain, temporary hair loss [1.5.3]	Should be taken with food [1.5.5]. Risk of liver problems and bone marrow suppression; requires monitoring [1.5.2, 1.5.5]. Avoid grapefruit juice [1.5.4].

Managing Side Effects and When to Seek Medical Help

For mild, common side effects, simple home care measures can provide relief.

For an upset stomach: Try eating smaller, more frequent meals and avoiding rich or spicy foods. Taking the medication with food might also help [1.8.1]. A heat pad on the stomach may ease cramping [1.8.1].
For diarrhea: It is important to drink plenty of fluids like water to prevent dehydration [1.8.1].
For dizziness or drowsiness: Avoid driving or operating machinery until you know how the medication affects you [1.6.2].

You should contact a doctor if side effects are severe, persistent, or worsen over time [1.2.1]. It is crucial to seek immediate medical help if you experience signs of a serious allergic reaction, such as hives, swelling of the face and throat, or difficulty breathing [1.3.1]. Other red-flag symptoms include severe abdominal pain, high fever, chills, unusual bleeding or bruising, yellowing of the skin or eyes (jaundice), or severe skin reactions like blistering [1.5.2, 1.9.1].

Conclusion

So, can pinworm medicine make you sick? Yes, it's possible, but for most people, the side effects are mild and short-lived, primarily involving gastrointestinal discomfort [1.4.5]. Over-the-counter options like pyrantel pamoate and prescription drugs like mebendazole and albendazole are highly effective at treating the infection [1.7.4]. Understanding the potential side effects helps you know what to expect and when it's necessary to consult a healthcare professional. Always follow the dosage instructions and complete the full course of treatment, which typically involves a second dose two weeks after the first to prevent reinfection [1.7.3]. Treating all household members simultaneously and practicing strict hygiene are essential for finally eradicating the parasites [1.4.2].

For more information on pinworm infections, you can visit the CDC's Parasites page.

Frequently Asked Questions

The most common side effects are gastrointestinal issues such as nausea, vomiting, stomach cramps, and diarrhea. Headache and dizziness can also occur [1.2.1].

Not always. Pyrantel pamoate (e.g., Pin-X, Reese's Pinworm Medicine) is available over-the-counter. Other effective medications, such as mebendazole and albendazole, require a prescription from a doctor [1.7.3].

For most people, side effects are mild and temporary, often resolving on their own as your body adjusts to the medication [1.4.5]. If symptoms persist or are severe, you should consult a doctor [1.2.1].

Yes, although it is rare, a serious allergic reaction is possible. Symptoms can include rash, hives, itching, swelling (especially of the face, tongue, or throat), severe dizziness, and trouble breathing. Seek immediate medical help if this occurs [1.2.3, 1.3.1].

Albendazole should be taken with food [1.5.5]. For other medications like mebendazole, taking it after a meal may help ease stomach discomfort [1.8.1]. Pyrantel pamoate can be taken with or without food, milk, or juice [1.2.5].

A second dose, usually taken two weeks after the first, is recommended to kill any worms that have hatched from eggs since the initial treatment, helping to prevent a full-blown reinfection [1.7.3].

Yes, some pinworm medications, like pyrantel pamoate, can cause drowsiness or dizziness [1.2.1]. Albendazole can also cause unusual tiredness [1.5.4]. You should avoid driving until you know how the medication affects you [1.6.2].