What are the side effects of mastectomy? What about breast reconstruction?

When considering what kind of surgery to have, it is important to know that there are potential side effects common to all surgical procedures. Any surgical procedure carries a risk of infection, poor wound healing, bleeding, or a reaction to the anesthesia. Also, pain and tenderness in the affected area is common, usually only in the short term. Because nerves may be injured or cut during surgery, most women will have numbness and tingling in the chest, underarm, shoulder, and/or upper arm.
Removal of lymph nodes under the arms may be performed. This can lead to pain and arm swelling, called lymphedema, which can last a long time and be debilitating.
Breast reconstruction after mastectomy often requires multiple additional surgeries and significant recovery time. Companies that make breast implants have informed the FDA that 1 in 4 patients whose breasts were reconstructed with implants have at least one additional surgery within 3 years. With tissue flap surgery, healing can take a long time, and pain can last for months.
Keep in mind that the side effects of treatment vary for each person. Some women have many side effects or complications, others may have very few. Pain medication, physical therapy, and other strategies can help women manage side effects and recovery.

If I have a mastectomy, does that mean I won’t need other treatment after surgery?

Not necessarily. Some women with early-stage breast cancer who have mastectomy might also need radiation therapy, chemotherapy, or other treatment.
See, "Will I need treatment after surgery?" to learn about adjuvant therapy.