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Possible Complications After Bariatric Surgery

As with any type of surgery, weight loss surgery has its risks. Some of these complications are common and mild, but some will require immediate or eventual medical attention.

Nausea and Vomiting

Most bariatric surgery patients will experience nausea and vomiting at some point as they adjust to new eating habits, such as when to eat and drink and how much to consume. However, contact your bariatric surgery team if you're vomiting frequently or if you can't determine the cause of your nausea or vomiting.

Gastrointestinal Issues

It's common to experience constipation and gas/bloating after bariatric surgery. However, chronic constipation can lead to intestinal blockage and other serious issues, so it's important to address it as soon as possible. Here are some ways to stay regular after surgery:

  • Use milk of magnesia, MiraLAX, or a glycerin suppository as needed (these laxatives should not be used for the long term).
  • Eat 1/8 to 1/4 cup of unsweetened applesauce, Cream of Wheat, or unsweetened pureed prunes a day until you're regular.
  • Add 1 Tbsp of raw wheat bran or ground flaxseed to your protein shakes, unsweetened applesauce, hot cereal, or refried beans every day until you're regular.
  • Drink a lot of water, but remember to sip and to not drink beverages with your meals.

If you're having gas pains that don't go away with exercise, try simethicone drops or Gas-X. Contact your physician if these methods don't ease gas production.

Dumping Syndrome

If you eat and drink at the same time, or if you eat high-fat foods or sweets, you may experience severe diarrhea, nausea, light-headedness, and stomach cramps. This is why bariatric surgery patients are strongly encouraged not to drink anything with meals, limit sugar intake, and eat low-fat foods.

Weight Gain

While bariatric surgery is highly effective for weight loss, it's only a tool. To maintain results, you have to adhere to recommended diet restrictions, eating habits, and lifestyle changes. If you're struggling with weight gain after surgery, contact your bariatric surgery team or join a bariatric surgery support group.


Low blood sugar can occur after bariatric surgery, but usually happens long after having the procedure. If you feel dizzy, clammy and sweaty, and like you may pass out, contact your bariatric surgery team. If hypoglycemia is left untreated, it can lead to seizures.


Tightening or stricture of the opening between your stomach and intestine can occur after gastric bypass. Commonly occurring four weeks after surgery, symptoms include vomiting after eating or drinking that gets worse over time, the sensation that food is stuck in your esophagus, not being able to tolerate certain foods, being unable to tolerate solid foods after the initial liquid diet, and experiencing pain when eating solid foods. If you have any of these symptoms, contact your bariatric surgery team immediately. While this can be treated with an outpatient procedure, it needs to be treated as soon as possible.

Hair Loss

Rapid weight loss commonly causes hair thinning, and hair loss often occurs after bariatric surgery because you're not eating enough protein daily. Try to consume at least 60 grams of protein a day or the amount your dietitian or physician has recommended.

Vitamin Deficiencies

Vitamin deficiencies are common when patients don't take vitamins or choose to take a generic over-the-counter multivitamin. To prevent vitamin deficiencies, bariatric multivitamins are available.

Vitamin/Mineral Lab to Request Pre-op 2 months post-op 6 months post-op Annually post-op Signs of Deficiency
Vitamin B1 Thiamine (vitamin B1) Poor memory, irritability, tingling in extremities (*treat with 100mg B1 daily, if you suspect a deficiency without a lab draw)
Vitamin B12 B12 cobalamin, methylmalonic acid Anemia, fatigue, muscle weakness, cognitive impairment
Folate Serum folate Anemia, red tongue, mental confusion, weakness, fatigue
Calcium Serum calcium, PTH, alkaline, phosphatase Bone loss, leg cramping, muscle weakness, osteoporosis
Vitamin A* Plasma retinol Night blindness, poor wound healing, loss of taste
Vitamin D Vitamin 25 (OH) D Osteomalacia, bone pain, tingling, fatigue
Vitamin E* Plasma alpha tocopherol Neurological damage, muscle weakness, gait disturbance
Vitamin K* PT 10-13 seconds Hemorrhage, easy bruising, bleeding gums
Iron Iron status, ferritin, TIBC Anemia, pale skin/nail beds, glossitis, fatigue, dysphagia
Zinc Serum zinc Hair loss, taste changes, diarrhea
Phosphorus Serum phosphorus Fragile bones, stiff joints
Copper* Serum copper RNY, DS RNY, DS Anemia, hair/skin/nail hypopigmentation
Magnesium Serum magnesium Loss of appetite, numbness/tingling, nausea, vomiting
Selenium* Serum selenium RNY, DS RNY, DS Infertility, muscle weakness, fatigue, hair loss, weakened immune system

* = with specific findings
Shaded areas indicate that it is not necessary unless indicated by physical assessment /specific findings; there is not data regarding copper or selenium post-Sleeve


Sores in the lining of the stomach or small intestine are possible at any time after bariatric surgery and cause severe, persistent nausea and pain, especially with eating. Early detection is key, so contact your physician if you're experiencing any symptoms. Ulcers can be treated with anti-ulcer medication such as Protonix or Prilosec.


Gastrointestinal leaks are possible up to one week after bariatric surgery, or after you're discharged from the hospital. If you experience any of these symptoms, call your surgeon's office immediately or go to an emergency room if it's after regular office hours:

  • Persistent left shoulder pain
  • Severe pelvic pain
  • Fever (over 101°)
  • Inability to urinate or empty your bowels
  • Anxiety, sweating, chills
  • Nausea and vomiting
  • Persistent hiccups (with other symptoms)
  • Color change in drainage from incisions

When to Seek Immediate Medical Assistance

You should call your bariatric surgeon or seek emergency care if you experience any of the following:

  • Chest pain that's getting worse
  • Difficulty breathing when at rest
  • Fever over 101°
  • Pain, redness, or swelling in the legs (indicative of blood clots)
  • Increased drainage, swelling, or pain at incision sites
  • Incision drainage that is green or pus-like, or has a foul smell (normal drainage is yellowish-red in color and odorless)

Follow-Up Appointments

Your Kelsey-Seybold bariatric team is here to support you at every stage of your weight loss journey. After surgery, you will need to be closely monitored to help prevent complications or to identify and treat complications if they do arise. For this reason, as part of your post-surgery care plan, you'll be scheduled for a series of follow-up appointments with your bariatric surgeon. During these visits, your health and weight statuses will be monitored, and any issues will be addressed.

In addition to bariatric care appointments, you'll also need to schedule a follow-up appointment with your primary care physician two to three weeks after surgery. You'll also see a Kelsey-Seybold dietician two to three months after surgery.

Bariatric Support Group

All pre-operative and post-operative patients, as well as friends and family members of patients, are encouraged to attend a local support group near you and find online support groups.

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