Pyrvinium (Oral)

Pyrvinium is often prescribed to those suffering from pinworms, however, there are a variety of different side effects and interactions that could occur, which you can find more information about here.


If you suffer from pinworms (or enterobiasis), then you will have been prescribed Pyrvinium as a means to help treat it. Do note that you should not try and obtain Pyrvinium on its own as it is only available following a doctor's prescription. Also, it is only used to treat pinworms, and not any other form of worm infection, including tapeworm or roundworms.

Below you can find full information regarding any potential side effects, and what to do if unwanted effects do occur. If other members of your household have been affected by this condition, then they will need to be treated at the same time you are.

Conditions Treated

  • Pinworms (enterobiasis)

Type of medicine

  • Liquid

Side effects

Pyrvinium, just like most drugs, can potentially cause a variety of different side effects. Some side effects can be less worrying and largely dealt with throughout your course of treatment. However, there are also some which are more distressing, and which require immediate medical attention. If you suffer from any of the effects listed directly below, then contact your doctor immediately.

Directly below here, you can find a further list of possible side effects which, though uncomfortable, aren't necessarily a cause for major concern. If you suffer any of these and would like to try and have the symptoms relieved, then you can, of course, contact your doctor. They may be able to alter your dosage someway in order to limit these unwanted effects.


  • Vomiting and nausea
  • Diarrhea
  • Stomach cramps
  • Increased skin sensitivity to sunlight

You will also likely notice that your stools will become red whilst you are taking Pyrvinium. This also applies to any vomit you bring up as well. The redness is not a cause for concern and is instead just a dye from the medicine. Just be careful to try not to get any on your clothes as it can stain.

Beyond this, you may experience some other less common side effects. If you do believe you are experiencing side effects as a result of the Pyrvinium and they are causing you concern, then you can contact your doctor for further guidance.


Below you will find the typical adult dosage of pyrvinium. However, there is a good chance your prescription will differ, and that is because of your differing medical state. Do not attempt to change your dosages unless otherwise instructed to do so by your doctor. Your exact prescription will depend on a number of things, not limited to the exact strength of the medication and the frequency with which you are required to take it.

When taking Pyrvinium via oral suspension:

  • Adults and children: You will be required to take a single dosage every 2 to 3 weeks. The exact dose is calculated by your doctor and calculated via your bodyweight.

Pyrvinium is quite straightforward to administer, and there are no special requirements you need to fulfill before, during or after you take it.

You will be provided with an accurate measuring spoon with which to measure the exact amount you are taking. Be sure to use this as opposed to any other household spoons which are not necessarily as accurate.

Pinworms are known to spread very easily, and it is likely your whole household could be infected. If so, you will all have been prescribed Pyrvinium in different quantities. Be sure to accurately measure and track everyone is receiving the correct dosages. Mixing up dosage amounts will decrease any benefits people could expect to receive and could increase the risk of unwanted side effects. Similarly, once the infection has cleared up, everyone will likely be required to go for one more course of treatment 2 to 3 weeks later, to ensure no re-infection occurs.

Even if you believe your symptoms have cleared, continue to take Pyrvinium until your doctor tells you to stop.


Pyrvinium Is known to react to a variety of different drugs. For that reason, you will need to first tell your doctor about all prescriptions, non-prescriptions, supplements and herbal remedies that you take. That way they can best identify any potential interactions and suggest means to avoid them. In some cases, interactions will occur and are unavoidable, but in others, a different medication may be prescribed instead.

The same applies to certain foods, or drink you may consume. Your doctor will ask you to clarify what your typical diet contains, as well as your intake of tobacco and alcohol. If any interactions may occur, then your doctor may alter your dosage or may require you to alter your diet in some way. They are best placed to advise you if that is the case.

Finally, your doctor will require you to tell them about your medical history. By getting a full understanding of any medical conditions you hold, they will be able to anticipate any such interactions with those and Pyrvinium. In such cases, they may need to prescribe a different drug or a largely reduced dosage.


Before being prescribed Pyrvinium, your doctor will want to know about any potentially harmful reactions that could occur due to any allergies that you have. Pyrvinium could exacerbate certain allergies to preservatives, dyes, foods, animals, or drugs. So it is best to be honest and open about any allergies you have.

There have been studies performed on the effects of using Pyrvinium on children. They have found that it is not necessarily likely to cause any different side effects. However, you should be aware that young children who weigh less than 10kg should exercise caution when taking this drug. Some older children do have an increased chance of having an upset stomach after taking large doses of Pyrvinium. Your doctor is best placed to advise the correct course of treatment for your child and any special measures that must be taken.

On the flipside, there haven't been many direct studies into the effects of Pyrvinium on geriatric patients. This is quite normal, as many drugs have not been examined in that way. Although, there is no reason to expect that there would be any greater chance of adverse side effects appearing in older patients. If you are older and do suffer from other medical conditions which are age-related, then your doctor may need to make some adjustments. However, that will need to be discussed with them prior to prescription.

If you are breastfeeding, then your doctor will need to weigh the intended benefits against any potential risks that could occur. However, there are not adequate studies that have been performed in determining an increased chance of infant risk when the mother is using Pyrvinium.

After taking Pyrvinium, if your symptoms do not improve within a few days, then you should contact your doctor and notify them. This is particularly true if you notice your condition getting any worse during that period.

Pyrvinium can cause an increase in the sensitivity of your skin to direct sunlight. Even after brief periods of time, you could experience severe sunburn, itching, redness, a rash or discoloration of your skin. For this reason, you should follow the protocol listed below for the 2 days after taking Pyrvinium.

  • Do not go into direct sunlight between 10 am and 3 pm.
  • Wear sunglasses, a hat and protective clothing when you are outside.
  • You should wear sunscreen that has an SPF of at least 15. If you have a fair complexion, then this may need to be higher. Your doctor will be able to advise you on which sunscreen would be most suitable.
  • Use a sunblock lipstick with an SPF that is at least 15.
  • Do not use any tanning booths, beds or sunlamps.

If for any reason, you suffer a reaction to the sun in this period, then contact your doctor for advice.

It is also worth being aware that, even after treatment with Pyrvinium, there is a chance your pinworms could return. To help prevent this happening, it is recommended you wash all of your pyjamas and bedding. Beyond this, your doctor will be able to recommend some steps to take that are most relevant to your circumstances.


You should keep your Pyrvinium stored at all times in a sealed container, and in a place that will not allow it to freeze. Instead, it should be at room temperature, away from direct sunlight, moisture and heat. It should be safely stored away from children, as it could have harmful effects on them. Once you have finished using your Pyrvinium, dispose of it in a safe method as instructed by your doctor. Never use any drugs or medication that is out of date.


If you suffer from pinworms, then it is common that your doctor may prescribe you Pervinium as a means to treat it. Before being prescribed the drug, your doctor will require you to undergo a full consultation to check and anticipate any possible interactions or side effects that may occur. If you do experience any unwanted and worrying side effects at any time, then you should contact your doctor for advice on how to relieve the symptoms.

There is a chance that pinworms could spread to other members of your family, as it is known to spread quickly and easily. If they have not yet been checked, then it may be worth doing so. Similarly, everyone affected will need to be treated at the same time. Your doctor will need to maintain appointments with your whole family to ensure everyone's condition has improved, and to avoid the infection occurring once more. Be sure to attend all such scheduled meetings as they are important.

Under no circumstances should you self-prescribe Pyrvinium, and instead it should only be taken following a prescription from your doctor. For any other questions you have, beyond what are listed and displayed here, speak directly to your doctor.


Last Reviewed:
January 31, 2018
Last Updated:
April 05, 2018
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