The treatment of head and neck cancer can lead to various complications, and the specific risks depend on factors such as the type and stage of cancer, as well as the chosen treatment modalities. Common complications may include:

1. **Difficulty Swallowing (Dysphagia):** Surgery or radiation therapy can affect the muscles and structures involved in swallowing, leading to difficulty in swallowing food and liquids.

2. **Speech Changes:** Surgery or radiation therapy may affect the vocal cords or other structures involved in speech, leading to changes in voice quality or difficulty in speaking.

3. **Xerostomia (Dry Mouth):** Radiation therapy can damage the salivary glands, resulting in reduced saliva production, which can lead to dry mouth. This can affect speech, chewing, and increase the risk of dental problems.

4. **Nutritional Issues:** Difficulty swallowing and changes in taste or appetite can lead to nutritional challenges. Maintaining proper nutrition is crucial for overall health and recovery.

5. **Changes in Taste:** Radiation therapy or certain medications can alter the sense of taste, leading to a metallic taste or other taste abnormalities.

6. **Fatigue:** Cancer treatment, especially radiation therapy and chemotherapy, can cause fatigue that may persist even after the treatment is completed.

7. **Infections:** Weakened immune function due to cancer treatment can increase the risk of infections. Chemotherapy and radiation therapy can also damage the mucous membranes lining the mouth and throat, making it easier for infections to occur.

8. **Skin Changes:** Radiation therapy can cause skin reactions in the treated area, including redness, dryness, and peeling.

9. **Lymphedema:** Surgery or radiation therapy can disrupt the normal flow of lymphatic fluid, leading to swelling in the head and neck region.

10. **Hearing Loss:** Depending on the location and extent of treatment, hearing loss may occur.

11. **Cognitive Changes:** Some cancer treatments, particularly certain chemotherapy drugs, may cause cognitive impairment or "chemo brain," characterized by difficulties in concentration, memory, and multitasking.

12. **Psychosocial Effects:** Dealing with cancer and its treatment can have emotional and psychological impacts. Patients may experience anxiety, depression, or changes in body image.

13. **Secondary Cancers:** There is a risk of developing secondary cancers, especially with certain types of radiation therapy and chemotherapy.

It's important to note that not all individuals will experience these complications, and the severity can vary. Patients undergoing head and neck cancer treatment should have open communication with their healthcare team to address and manage potential complications effectively. Additionally, supportive care and rehabilitation services are often integral parts of the overall treatment plan to improve the quality of life for individuals with head and neck cancer.