Complications of pinworm infections are rare but may include:

• Bacterial infection around the anus or of the skin in the genital area. This is usually due to skin being irritated or bleeding from itching in these areas.
• Pinworm infection of the vagina (vulvovaginitis).
• Pinworm infection of the urethra (urethritis) or a secondary infection of the urinary tract (cystitis).
• Pinworm infection of the internal female sex organs (endometritis, salpingitis, and oophoritis).
• Inflammation inside the abdomen (peritonitis).
• An area of inflammation with a pocket of pus within the lower part of the intestine (rectal abscess).
• Irritation of the tissue covering the inside of the eyelid and eyeball (conjunctival sac irritation).
• Long-term inflammation and scar tissue (granulomas) in the prostate or liver. This is very rare.
  • Prostate granulomas occur when pinworms travel up the urethra and settle in the prostate gland.
  • Liver granulomas occur in females if pinworms travel through the reproductive system, get into the abdomen, and attach to the liver.