Medically Reviewed by Dr. Carmen Fong, MD, FACS
Anorectal pain (pain in or around the anus and rectum) is a very common and often distressing side effect for people undergoing colorectal or anal cancer treatment. Discomfort may range from mild irritation to intense burning or sharp pain, particularly during or after bowel movements.
Both colorectal cancer and anal cancer treatment, such as surgery or radiation, frequently involve the lower digestive tract, which makes anorectal symptoms especially common. The good news: this type of pain is well recognized in cancer care; there are clear reasons why they occur, and many supportive care strategies can help improve your comfort and quality of life.
This guide explains why anorectal pain happens, what relief options are commonly recommended, and how gentle topical creams, like Bummed creams, may help ease external skin irritation during treatment.
Important: This article is for educational purposes only and does not replace medical advice. Always check with your oncology team before using new products, especially during radiation therapy or if skin is broken.
Why anorectal pain occurs during colorectal and anal cancer treatment
Radiation-related inflammation (radiation proctitis and radiation dermatitis)
Radiation therapy is a primary treatment for anal cancer and is also commonly used for rectal cancer. Pelvic radiation can irritate both:
- The rectum, causing radiation proctitis
- The anal canal and surrounding skin, causing radiation dermatitis
According to the National Cancer Institute, radiation proctitis can cause rectal pain, urgency, diarrhea, bleeding, and discomfort during bowel movements, and symptoms may appear during treatment or months to years later.
The American Society of Clinical Oncology (ASCO) notes that gastrointestinal and anorectal toxicities from pelvic radiation may be acute or chronic, and severity varies based on radiation dose and individual factors.
For people receiving anal cancer radiation, external anal skin irritation is especially common due to direct exposure.
Diarrhea and frequent bowel movements
Chemotherapy and radiation, particularly for anal cancer, commonly cause diarrhea and bowel urgency. Frequent loose stools increase:
- Moisture
- Friction
- Exposure of sensitive skin to irritants
Oncology nursing guidelines from BC Cancer emphasize that ongoing diarrhea can rapidly break down perianal skin and recommend early protective skin care to reduce burning and pain.
Constipation, hemorrhoids, and anal fissures
Some people experience constipation during cancer treatment, often due to pain medications, dehydration, reduced activity, or treatment side effects. Hard stools and straining can worsen:
- Hemorrhoids
- Anal fissures (small tears in the anal lining)
- Muscle spasms that cause sharp pain
The National Cancer Institute’s GI Complications PDQ identifies constipation and diarrhea as common treatment-related complications in cancer care.
Surgery-related changes
Surgery for colorectal cancer—and less commonly for anal cancer—can temporarily or permanently change bowel habits, stool consistency, and nerve sensitivity. These changes may increase anorectal discomfort during recovery, especially when bowel movements are frequent or loose. A common post-operative condition called low anterior resection syndrome (LARS) occurs when the part of the colon that has been reconnected causes significant bowel changes and discomfort.
Infection or other treatable causes
Cancer treatments can weaken tissue defenses. The National Cancer Institute cautions that symptoms similar to radiation proctitis may also be caused by infection or other conditions, underscoring the importance of medical evaluation if symptoms worsen or change.
When to contact your oncology team right away
Contact your care team urgently if you experience:
- Severe or rapidly worsening anorectal pain
- Fever or chills
- Heavy or persistent rectal bleeding
- Inability to pass stool or gas
- Signs of dehydration from ongoing diarrhea
Relief options for anorectal pain during colorectal and anal cancer treatment
Treating the underlying cause
Effective relief starts with understanding why the pain is happening. Radiation-related inflammation, diarrhea, constipation, or skin breakdown may each require different approaches.
ASCO emphasizes that management of pelvic radiation side effects is individualized and often involves a combination of medical treatment and supportive care.
Gentle cleansing and skin protection
Supportive oncology care commonly recommends:
- Rinsing with warm water after bowel movements
- Avoiding scented wipes or harsh soaps
- Patting (not rubbing) the area dry
- Protecting the skin barrier to prevent breakdown
These steps are specifically highlighted in oncology diarrhea management guidelines as essential for reducing perianal irritation.
Managing stool consistency
Both extremes worsen pain:
- Loose stools → burning and skin breakdown
- Hard stools → tearing and sharp pain
The NCI GI Complications PDQ outlines clinician-directed strategies to manage constipation and diarrhea during cancer treatment.
Always consult your oncology team before using over-the-counter stool medications.
Comfort focused measures
Many people find additional relief from:
- Warm sitz baths in a bathtub
- Loose, breathable clothing
- Avoiding foods that worsen symptoms
- Limiting prolonged sitting when possible
How Bummed creams can support comfort during treatment
Anorectal pain during colorectal or anal cancer treatment can be very uncomfortable—and it’s not always just “skin irritation.”
For many people, the pain is caused by a combination of:
- Tight or spasming muscles inside the anus
- Inflammation and soreness from radiation or frequent bowel movements
- Small tears (fissures) or swollen veins (hemorrhoids)
- Sensitive tissue after surgery
Important use notes:
- Reapply after bowel movements as needed
- Avoid use on open sores unless approved by your care team
- During radiation therapy, ask your radiation oncology team about timing and approved topical products
Bummed creams are not a treatment for cancer or radiation injury, but they may help reduce everyday discomfort while underlying causes are being medically managed.
Frequently Asked Questions
Is anorectal pain common with anal cancer treatment?
Yes. Radiation therapy is a cornerstone of anal cancer treatment, and anorectal pain and skin irritation are well-documented side effects.
https://www.cancer.gov/about-cancer/treatment/side-effects/radiation-proctitis
Can radiation cause both internal and external pain?
Yes. Pelvic radiation can inflame the rectum and damage external anal skin, leading to multiple pain sources.
https://ascopubs.org/doi/10.1200/EDBK_323525
Why does diarrhea make anal pain worse?
Frequent loose stools increase moisture and irritant exposure, which can break down sensitive skin—especially during radiation therapy. http://www.bccancer.bc.ca/nursing-site/documents/4.%20diarrhea.pdf
Should I use topical creams during radiation?
Many people do, but product choice and timing matter. Always check with your oncology team.
When is pain an emergency?
Severe pain, fever, heavy bleeding, or rapidly worsening symptoms should be reported immediately.
Bummed content is for general education and should never replace professional medical advice that considers your individual health. If you think you’re experiencing a medical emergency, call 911 or head to the nearest emergency department.
Prescription products require an online consultation with a physician who will determine if a prescription is appropriate.