In Canada—

Another commonly used name is viprynium.

• Anthelmintic, oral-local

Pyrvinium (peer-VIN-ee-um) is used to treat pinworms (enterobiasis). It will not work for other types of worm infections (for example, roundworms or tapeworms).

Pyrvinium is available only with your doctor's prescription, in the following dosage forms:

Oral
• Oral suspension (Canada)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For pyrvinium, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to pyrvinium. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Pyrvinium has not been studied in pregnant women or animals. However, pyrvinium has not been reported to cause birth defects or other problems in humans.

Breast-feeding—Pyrvinium has not been reported to cause problems in nursing babies.

Children—Pyrvinium has been studied in children and, in effective doses, has not been reported to cause different side effects or problems in children than it does in adults. However, because of limited experience, caution is recommended in children weighing less than 10 kilograms (22 pounds). Older children are more likely to have stomach upset after receiving large doses.

Older adults—Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults. Although there is no specific information comparing use of pyrvinium in the elderly with use in other age groups, this medicine is not expected to cause different side effects or problems in older people than it does in younger adults.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your health care professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.

No special preparations (for example, special diets, fasting, other medicines, laxatives, or enemas) are necessary before, during, or immediately after you take pyrvinium.

Use a specially marked measuring spoon or other device to measure each dose accurately. The average household teaspoon may not hold the right amount of liquid.

Pinworms may be easily passed from one person to another, especially among persons in the same household. Therefore, all household members may have to be treated at the same time to prevent their infection or reinfection. Also, all household members may have to be treated again in 2 to 3 weeks to clear up the infection completely. Make sure each family member takes the correct amount, since the dose may be different for each person.

To help clear up your infection completely, take this medicine exactly as directed by your doctor. Read the instructions on the label and follow them carefully. The amount of medicine you need is based on your weight. You must take the exact amount if the medicine is going to work. A second course of pyrvinium is usually required to clear up the infection completely.

Dosing—

The dose of pyrvinium will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of pyrvinium. If your dose is different, do not change it unless your doctor tells you to do so.

• For the oral suspension dosage form:
  • Adults and children: Dose is based on body weight and will be determined by your doctor. It is taken as a single dose and is repeated in 2 to 3 weeks.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not freeze oral suspension.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

If your symptoms do not improve within a few days, or if they become worse, check with your doctor.

Pyrvinium may cause your skin to be more sensitive to sunlight than it is normally. Exposure to sunlight, even for brief periods of time, may cause a skin rash, itching, redness or other discoloration of the skin, or a severe sunburn. For a day or two after taking this medicine:

• Stay out of direct sunlight, especially between the hours of 10:00 a.m. and 3:00 p.m., if possible.
• Wear protective clothing, including a hat. Also, wear sunglasses.
• Apply a sun block product that has a skin protection factor (SPF) of at least 15. Some patients may require a product with a higher SPF number, especially if they have a fair complexion. If you have any questions about this, check with your health care professional.
• Apply a sunblock lipstick that has an SPF of at least 15 to protect your lips.
• Do not use a sunlamp or tanning bed or booth.

If you have a severe reaction from the sun, check with your doctor.

In some patients, pinworms may return after treatment with pyrvinium. Washing (not shaking) all bedding and nightclothes (pajamas) after treatment may help to prevent this. Some doctors may also recommend other measures to help keep your infection from returning. If you have any questions about this, check with your doctor.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if the following side effect occurs:

• Rare
  • Skin rash 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• Rare
  • Diarrhea;  increased sensitivity of skin to sunlight;  nausea and vomiting;  stomach cramps 
  
  

This medicine is a dye and will color your stools red. This color is not harmful and will disappear in a few days. Pyrvinium may also stain clothing red. If vomiting occurs, the vomit will be red in color.

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.