“Why does my rectum itch after I urinate?”

Your anal itching may be the result of a certain skin condition, such as the following.

Dermatitis: There are several skin conditions that can cause itchy skin anywhere on the body, including the anus.
Hygiene: If you wash too much, you could be drying out the skin, leading to itching. If you're not washing enough, stool buildup can also cause itching.
Anal itching may be due to an infection, such as the following.
Parasitic: There are a variety of parasitic infections that can cause anal itching symptoms, such as pinworms.
Sexually transmitted: Certain sexually transmitted infections and diseases can lead to anal itching.
Diabetes: Candidiasis is linked to diabetes, which can cause itching.
Inflammatory bowel syndrome

Sorry to hear you experience an itch around the anus after peeing. As usual, a comprehensive evaluation with detailed history taking and physical examination is dearly needed. To get an overview of what you should do and prepare for a sensible diagnosis and care, please review the page at http://www.formefirst.com/eNewsletter06.html. Besides, other pages in www.formefirst.com could be useful for your long-term healthy care. I wish you well in daily living and medical care.

Check for dribbling after voiding. Urine contact with skin might result in this irritation