Complications and side effects
Understanding the types of complications you can have will help you decide whether surgery is right for you. It will also help you learn to prevent, recognize, and manage complications if they do occur. Use the following tool to learn about possible side effects and complications of surgery, including information on how to prevent, identify, and manage symptoms.
Explore the possible complications and side effects to learn more.
Minimize your risk of complications
- Follow the meal plan after surgery, including taking vitamin and mineral supplements every day
- Keep up with a regular physical activity routine
- Attend all follow-up care appointments
Calcium
Calcium supports the structure of bones and teeth, helps with muscle function, and coordinates nerve transmission and hormone control. Prolonged deficiency can increase bone loss and eventually lead to osteoporosis, which increases the risk for fractures of the hip, vertebrae, wrist, pelvis, and other bones.
Symptoms of deficiency
- Muscle aches
- Cramps in the back and legs
- Scaly skin
- Brittle nails
- Coarse hair
- Tingling in the lips, tongue, fingers, and feet
- Abnormal heart rate
Dehydration
Dehydration is the most common reason patients need to return to the hospital after surgery. During the first few weeks after surgery, patients often struggle to drink enough, but it’s extremely important to get enough fluids during this time.
Symptoms
- Dark, strong-smelling pee
- Dry mouth
- Headache
- Nausea
- Fatigue
- Muscle aches
To prevent it
- Sip 1–2 ounces of liquids slowly every 10–15 minutes or more as tolerated, working up to 8 cups (64 ounces) a day.
- Choose low-calorie (no more than 5 calories per 8 ounces), low-sugar liquids like water or herbal tea.
If it happens
- If dehydration is mild: Replenish the fluid in your body by having clear fluids like water, clear broths, ice, or ice pops.
- If dehydration is severe: You may need to go to the Emergency Department to get intravenous fluids. Tell them the type of surgery you had.
Folate (Folic Acid)
Folate plays an important role in cell function. Deficiency can increase the risk of heart disease, cognitive decline, dementia, Alzheimer’s disease, depression, and poor response to antidepressants. In pregnant women, low folate may lead to birth defects or preterm birth.
Symptoms of deficiency
- Anemia
- Weakness
- Fatigue
- Difficulty concentrating
- Irritability
- Headache
- Heart palpitations
- Shortness of breath
- Sores/shallow ulcers
- Changes in skin, hair, and fingernail color
Iron
Iron helps transfer oxygen from the lungs to muscles and supports metabolism. It’s important for growth, development, normal cell function, and the creation of hormones and connective tissue. Prolonged deficiency can lead to heart problems. In pregnant women, iron deficiency may lead to premature and low birth weight babies.
Symptoms of deficiency
- Anemia
- Fatigue
- Weakness
- Pale skin
- Dizziness
- Shortness of breath
- Irregular body temperature
- Increased desire to eat ice and non-food items
- White fingernails
Protein
Protein is important for healing and muscle building. Low levels of protein can lead to deterioration of muscles. Prolonged protein deficiency can lead to liver problems.
Symptoms of deficiency
- Low bone density
- Muscle contractions
- Pain
- Spasms
- Hair loss
- Burning or prickling sensation in the hands, arms, legs, or feet
- Swelling in face and body (called edema)
Vitamin A
Vitamin A is important for vision, immune function, and reproductive health. It also helps with heart, lung, kidney, and other organ function. Prolonged deficiency can lead to vision problems, including night blindness or total blindness, skin disorders, infections, diarrhea, and lung disorders.
Symptoms of deficiency
- Dry skin and hair
- Itchy skin
- Broken fingernails
- Dry eyes
- Night blindness or inability to see when going from light to dark
Vitamin B1 (Thiamine)
Thiamine supports growth and development and cell function. Deficiency can lead to serious neurological problems.
Symptoms of deficiency
- Loss of appetite
- Weakness
- Pain in the limbs
- Shortness of breath
- Swollen feet or legs
- Problems with coordination
- Rapid heart rate
Vitamin B12
Vitamin B12 is needed for creating red blood cells, neurological function, and DNA synthesis. Deficiency can increase the risk of heart disease, cognitive decline, dementia, and Alzheimer’s disease.
Symptoms of deficiency
- Anemia
- Fatigue
- Weakness
- Loss of appetite
- Weight loss
- Numbness and tingling in the hands and feet
Vitamin D
Vitamin D is important for the absorption of calcium. It helps with bone growth and strengthening. It also regulates cell growth, neuromuscular and immune function, and reduction of inflammation. Prolonged deficiency leads to serious bone disorders like osteopenia and osteoporosis.
Symptoms of deficiency
- Bone pain
- Muscle weakness
- Fatigue
Internal Hernia
An internal hernia occurs when part of the intestine makes its way into a surgical cut. This is very serious because it can cause part of the intestine to die.
This is more common with gastric bypass.
Symptoms
- Mild to severe stomach pain
- Nausea and vomiting
- Inability to have a bowel movement or pass gas
To prevent it
- Follow the post-surgery meal plan
- Attend all follow-up appointments
If it happens
- Go to the Emergency Department immediately. Tell them the type of surgery you had.
- Call your Kaiser Permanente care manager as soon as possible.
Leak
A leak can form inside the body anywhere the stomach or intestine has been cut.
Symptoms
- Rapid heart rate
- Fever
- Stomach pain
- Back pain
- Hiccups
- Nausea
- Vomiting
- Low blood pressure
- Restlessness
To prevent it
- Follow the post-surgery meal plan.
- Attend all follow-up appointments.
If it happens
- Go to the Emergency Department immediately. Tell them the type of surgery you had.
- Call your Kaiser Permanente care manager as soon as possible.
Pneumonia
Pneumonia (infection of the lung tissue) can sometimes occur after major surgery.
Symptoms
- Cough
- Fever
- Shortness of breath
- Fatigue
To prevent it
- Walk or get some form of physical activity.
- Attend all follow-up appointments.
- Make sure asthma is under control before surgery.
- Use an incentive spirometer (device that helps keep lungs healthy after surgery) while in the hospital.
If it happens
- Go to Urgent Care or the Emergency Department. Tell them the type of surgery you had. Sometimes a gastric sleeve surgery leak can be confused with pneumonia.
- Call your Kaiser Permanente care manager as soon as possible.
Stricture (Stenosis)
This occurs when there’s a tightening and narrowing of the new opening between the stomach and intestines after surgery. It may cause vomiting after eating or drinking.
This is more common with gastric bypass.
Symptoms
- Nausea
- Vomiting undigested food, especially right after eating
- Dehydration from nausea and vomiting—lightheadedness and weakness
- Trouble swallowing
- Feeling of fullness in the upper middle of the stomach after eating that lasts a long time
- Trouble eating certain foods
To prevent it
- Do not smoke, drink alcohol or caffeine, or take NSAIDs or steroids.
- Follow your health care team’s instructions about when and what to eat after surgery.
If it happens
- Go to the Emergency Department immediately. Tell them the type of surgery you had.
- Call your Kaiser Permanente care manager as soon as possible.
Ulcer
Ulcers are tiny holes that form on the edge of the new stomach (pouch). This is more common with gastric bypass.
Symptoms
- Stomach pain, often specifically in the middle of the upper abdomen, right at the bottom of the breastbone
- Nausea
- Vomit that looks like coffee grounds or red blood
- Black and/or bloody stools
To prevent it
- Follow the post-surgery meal plan. Attend all follow-up appointments.
- Do not smoke, drink alcohol or caffeine, or take NSAIDs or steroids.
If it happens
- If you think the ulcer is bleeding, go to the Emergency Department immediately. Tell them the type of surgery you had.
- Call your Kaiser Permanente care manager as soon as possible.
Wound Infection
Wound infection can occur with any surgery if the incision site is not kept clean and dry.
Symptoms
- Redness, discharge, smell, or tenderness at the incision
- Fever
To prevent it
- Keep your wound clean and dry.
- Wash your hands before and after any wound care.
- Check your wound often to see if there are any changes.
If it happens
- Go to Urgent Care or the Emergency Department. Tell them the type of surgery you had.
- Call your Kaiser Permanente care manager as soon as possible.
Constipation
Constipation may occur in the first couple weeks after surgery because you will not be eating solid food and not getting much fiber. This is OK because your stomach pouch is still healing. Also, some pain medications can increase constipation. If constipation is severe or lasts beyond the first 3 months, you may need to check what you are eating and how much water you are drinking.
If you are using diuretics for a medical condition such as chronic kidney disease or heart failure, check whether you need to adjust your medication with your doctor.
Symptoms
- Increased bloating, gas, and abdominal discomfort
- Lumpy or hard stools
- Straining to have bowel movements
- Fewer than 3 stools a week
- Feeling like there is a blockage that prevents bowel movements
To prevent it
- Stay hydrated. Sip fluids throughout the day except for 30 minutes before and after eating. If your urine is darker than pale lemonade, you may not be drinking enough.
- Avoid caffeine and diuretics (sometimes called water pills). These medications add water to your urine and can make it look a pale yellow. This usually means you are hydrated, but you could actually be dehydrated.
- Get regular physical activity. Walk for 30 minutes a day.
If it happens
- Get enough fluids (at least 64 ounces a day; more if you are tall or very active).
- Avoid diuretic medications and caffeine.
- If the constipation does not get better in 2–3 days, call your Kaiser Permanente care manager.
Cross Addiction
After surgery, there’s an increased risk for addiction transfer. This occurs when someone trades compulsive eating for other compulsive behaviors. It’s important to understand the risks and signs of addiction and know how to get help.
Learn more about cross addiction and bariatric surgery.
Symptoms
- Needing more of the substance or behavior to get the same effect
- Doing a behavior or using a substance longer or in higher amounts than planned
- Not being able to cut down, even when you want to
- An increase in negative consequences caused by the use or behavior (issues with self, family, friends, work, and/or legal problems)
- Others have suggested that you stop or cut down
- An increase in hiding or covering up the behavior or use
- An increase in feelings of guilt and shame
- Craving or having a strong desire or urge for the substance or behavior
- Withdrawing from important social, job-related, or recreational activities because of substance use
To prevent it
- Make the healthy choice the easy choice (remove trigger foods or alcohol from the home, etc.).
- Keep a food and drink log.
- If you’ve ever struggled with addiction, get help before surgery.
If it happens
If you have any signs of addiction, get help immediately. There are many resources at Kaiser Permanente and elsewhere that can help prevent addiction transfer or get you back on track.
Dumping Syndrome
Dumping syndrome occurs when the solid parts of a meal get “dumped” directly from the stomach into the small intestine without being digested. There are two types:
- Early Dumping Syndrome: Within 1 hour after eating
- Late Dumping Syndrome: 2–3 hours after eating (also called reactive hypoglycemia)
This is more common in gastric bypass.
Symptoms
Early Dumping Syndrome
- Bloating and stomach cramps
- Nausea
- Diarrhea
- Rapid heartbeat
- Sweating
- Dizziness or fainting
- Hyperglycemia (high blood sugar)
Late Dumping Syndrome
- Hunger
- Confusion
- Fatigue
- Sweating
- Rapid heartbeat
- Tremors or fainting
To prevent it
Follow the post-surgery meal plan.
- Don’t eat fatty, greasy, or fried foods.
- Avoid simple sugars, fats, and alcohol.
- Eat and drink slowly.
- Chew thoroughly.
- Drink liquids between meals (wait at least 30 minutes before and after eating).
If it happens
Dumping syndrome can usually be fixed by changing your diet and following the post-surgery meal plan.
Body Dysmorphia
Body dysmorphic disorder happens when you can’t stop focusing on what you think are defects or flaws in your appearance. It may cause you to feel so ashamed or anxious that you have significant difficulty functioning.
Symptoms
- Obsession about appearance lasting at least 1 hour a day
- Focus on body imperfections
- Avoiding mirrors or constantly checking mirrors
- Skin picking
- Excessive grooming
- Excessive exercise
To prevent it
- Set realistic expectations for weight loss after surgery.
- Practice self-care, self-gratitude, and self-compassion.
- Get help when needed.
- Attend support groups.
If it happens
Get help as soon as you can. It will allow you to not feel alone.
Cold Water Pain
Some people find cold beverages painful to their new stomach pouch, so they tend to tolerate warmer drinks best. This usually goes away in the first couple of weeks.
Symptoms
Pain when drinking cold fluids
To prevent it
- Get enough fluids (64 ounces/8 cups) throughout the day. Sip 1–2 ounces of liquids slowly every 10–15 minutes or more as tolerated, working up to 8 cups a day.
- Try warmer fluids.
If it happens
- Try warmer drinks, such as water or decaffeinated tea.
- If the symptoms don’t get better in the first couple of weeks after surgery, call your Kaiser Permanente care manager.
Disordered Eating or Eating Disorders
Having surgery without addressing the emotional attachment to food may lead to eating disorders after surgery.
Symptoms
- Severe calorie restriction (more than recommended on the post-surgery meal plan)
- Restricting food choices
- Intense fear of gaining weight
- Loss of control of eating behavior
- Compensatory behaviors like over-exercising, vomiting/purging, using laxatives or diuretics, chewing and spitting, forced dumping syndrome
- Perfectionist thinking or behavior
- Feeling out of control
To prevent it
- If you have a history of trauma, abuse, or neglect, make an appointment to see a therapist to start working on these issues before surgery.
- Attend a Kaiser Permanente or community support group.
If it happens
Get help as soon as you can. It will allow you to gain control and not feel alone.
Excess Skin
Many people lose so much weight that they end up with loose or sagging skin. This does not go away by itself, and most people are left with extra skin.
Excess skin affects everyone differently, and the amount you’ll have after surgery depends on many things, such as your weight before surgery, age, smoking history, and genetics.
Excess skin can cause other problems if not kept clean.
Symptoms
- Chafing or rashes
- Infections
To prevent it
- Keep excess skin, especially the underside, clean and dry.
- Wear clothes that fit properly.
- Get regular physical activity.
If it happens
- If you notice any rash or signs of infection, call your bariatrician or care manager immediately.
- It’s important to know what your health plan does and does not cover when it comes to excess skin.
GERD or Acid Reflux
Gastric bypass surgery is more likely to resolve GERD issues, but gastric sleeve surgery can make it worse for a time. GERD occurs when a weak muscle lets food and acids move back up (reflux) into the esophagus instead of keeping them in the stomach.
Symptoms
- Heartburn
- Chest pain
- Trouble swallowing
- Sensation of a lump in your throat
To prevent it
- Follow the post-surgery meal plan.
- Avoid spicy foods.
- Avoid citrus and tomatoes or tomato products.
- Don’t drink with meals.
If it happens
Gout
Gout is a type of arthritis. It can cause sudden pain, stiffness, and swelling in joints. There is an increased risk of gout attacks after surgery.
Symptoms
- Joint pain, especially in the hands, ankles, and feet
- Joint swelling, burning, redness, and tenderness
To prevent it
- Stay hydrated by sipping 1–2 ounces of liquids slowly every 10–15 minutes or more as tolerated, working up to 8 cups a day.
- Avoid red meat.
- If you’ve had a gout flare in the past, make sure to take your medication (usually allopurinol) before and after surgery.
If it happens
Go to your personal doctor or Urgent Care.
Hair Loss
Hair loss after surgery is very common. Whenever the body is put through an extremely stressful state, such as surgery or rapid weight loss, it stops putting energy into things that aren’t necessary to live, like hair growth.
Symptoms
Hair loss 3–6 months after surgery
To prevent it
- Follow the post-surgery meal plan, focusing on getting enough protein.
- Take your vitamin and mineral supplements.
If it happens
- When hair loss occurs 3–6 months after surgery, it’s most likely the result of the stress of major surgery and low calorie intake without enough protein (at least 60–80 grams a day).
- If it occurs or continues after 6 months, you could have a more severe deficiency in protein, iron, or other nutrients. If this happens, call your Kaiser Permanente care manager.
Kidney Stones
There is an increased risk for kidney stones after surgery.
Symptoms
- Sudden and significant side pain that may radiate to the groin
- Back pain
- Nausea or vomiting
- Fever and chills
- Urine with a bad smell
- Cloudy urine
- Possible blood in the urine
To prevent it
- Stay hydrated by sipping 1–2 ounces of liquids slowly every 10–15 minutes or more as tolerated, working up to 8 cups a day.
- Take calcium citrate supplements with food.
If it happens
Go to the Emergency Department immediately. Tell them the type of surgery you had.
Lactose Intolerance
Lactose intolerance may occur temporarily after surgery, even if you have never had a history of it.
Symptoms
Gas, bloating, cramping, and diarrhea after eating soft dairy products such as milk or cottage cheese
To prevent it
Follow the post-surgery meal plan. Track what you’re eating and how it makes you feel. This can help you recognize foods that you may not be able to tolerate.
If it happens
- Follow the post-surgery meal plan and replace dairy products with lactose-free alternatives such as unsweetened soy or nut milk.
- Try using a protein supplement that doesn’t have lactose.
Protein Malnutrition
Protein malnutrition is a serious complication. Protein is a major building block for your body. There can be serious health consequences if you don’t get enough protein regularly.
Symptoms
- Tiredness
- Weakness
- Hair loss
- Edema (swelling)
- Irritability
- Hearing loss
- Frequent illnesses
- Gaunt looking (thin/sickly)
To prevent it
- Follow the post-surgery meal plan and make sure you follow the protein supplement recommendations.
- Take your vitamin and mineral supplements every day.
- Attend all your follow-up appointments and get your labs done regularly.
- Consider tracking your protein to make sure you are getting enough.
If it happens
Talk to your Kaiser Permanente care manager or bariatrician.
Vitamin and Mineral Deficiencies
Surgery limits the amount of food you can eat, and it also limits the nutrients that your body can absorb. Despite taking supplements and following the post-surgery meal plan, you can become deficient in vitamins and minerals, which can have serious health consequences.
The most common deficiencies after surgery include vitamin B12, vitamin D, folic acid (important for pregnancy), calcium, iron, and thiamine (vitamin B1).
For more on vitamin and mineral deficiencies, go to nutrition-related complications.
Symptoms
Depending on the type of deficiency, you may have any of the following:
- Anemia
- Fatigue
- Weakness
- Nerve issues
- Cognitive difficulties/confusion
- Osteoporosis/frail bones
- Irritability
- Hair loss
- Delayed healing
To prevent it
- Follow the post-surgery meal plan.
- Take your vitamin and mineral supplements every day.
- Attend all your follow-up appointments and get your labs done regularly.
If it happens
Talk to your Kaiser Permanente care manager or bariatrician. You may need additional vitamin and mineral supplements.
Blood Clots (Deep Vein Thrombosis and Pulmonary Embolism)
Blood clots in the legs (deep vein thrombosis) and clots that pass to the lungs (pulmonary embolism) can occur with any major surgery. This can be fatal, so it’s important to be aware of the symptoms and get medical attention immediately.
Symptoms
Deep Vein Thrombosis
- Pain in the leg that is not the same on both sides (asymmetric)
- Swelling in the leg
- Redness in the leg
- Feeling of warmth in the leg
Pulmonary Embolism
- Sudden shortness of breath
- Lightheaded or dizzy
- Rapid heart rate
- Coughing up blood
- Chest pain or discomfort with breathing or coughing
To prevent it
- Walk for at least 15 minutes continuously multiple times a day after surgery.
- Stay hydrated.
- Keep taking any blood thinner medications you may be prescribed.
If it happens
- Go to the Emergency Department immediately. Tell them the type of surgery you had.
- Call your Kaiser Permanente care manager as soon as possible.
Gallstones
A gallstone is a small, hard mass formed in the gallbladder. There is an increased risk of gallstones after surgery.
Symptoms
Upper right side abdominal pain that radiates to the right shoulder, usually associated with eating.
To prevent it
Take all medications your surgeon prescribes, which may include medications to prevent gallstones within the first 6 months.
If it happens
Go to the Emergency Department immediately. Tell them the type of surgery you had. Call your Kaiser Permanente care manager as soon as possible.
Common questions about excess skin
Excess skin is a very common side effect of surgery. Everyone reacts differently to having excess skin, but it’s important to be prepared for it and learn strategies to adjust, cope, or (possibly) remove it.
Does everyone have excess skin after surgery?
Think of your skin like a balloon. When you first blow it up, it’s small and tight, but as the air is let out it doesn’t return to the original shape. After surgery, your fat cells will shrink as you lose weight, but your skin still has the same surface area. That’s what causes loose or excess skin. You will have a lot of changes between 6 and 18 months after surgery. Your appearance depends on several things, including:
- How much weight you lose
- How quickly you lose weight
- Your age
- Your genetics
- Whether or not you exercise or smoke
How will excess skin affect me?
Possible medical issues
- Chafing
- Rashes
- Infection
Possible psychosocial issues
- Embarrassment
- Poor body image
Can I prevent or minimize excess skin after surgery?
A lot of factors determine excess skin, and not all of them are in your control. However, there are several things you can do:
- Lose weight before surgery.
- Follow the staged meal plan after surgery. Following a balanced diet will help you keep weight off, retain lean muscle, and feel good. Getting enough protein can help you maintain and build lean muscle, which can somewhat minimize loose skin.
- Take your vitamin and mineral supplements every day. Making sure to take your vitamin and mineral supplements every day is key. Vitamins such as C, A, E, K, and B-complex, and minerals such as zinc are all important for skin health.
- Stay hydrated with water. After completing your post-surgery diet progression back to solid foods, you should be drinking at least 64 ounces (8 cups) a day. Drinking plenty of water makes your skin healthier and may make your skin more elastic (tight).
How can I manage excess skin?
Skin care
Your skin is an organ, just like your liver, heart, and kidneys. Taking care of it is important.
- Keep your skin moisturized.
- Use sunscreen.
- Keep your skin, especially the sagging areas, clean and dry.
To keep skin folds dry, try the following tips
- Use antiperspirant sprays or roll-ons. (Test a small area of skin first to be sure it doesn’t cause irritation. Do not test if the skin is already irritated.)
- Try absorbent powder, including cornmeal (available in the pharmacy foot care section).
- Use a hair dryer on a cool setting 2 to 3 times a day.
Compression garments
Certain types of clothes can help minimize the appearance of excess skin after surgery.
Excess skin removal surgery
Even if you follow all the recommendations, it’s realistic to expect that you will still have some excess skin after surgery. For some people, this is totally fine, but it may really bother others. In such cases, some people are interested in excess skin removal surgery. Not all patients qualify for excess skin removal.
Some examples of common areas considered for surgery include:
- Abdomen: Excess abdominal skin that covers the genital region.
- Upper arm: When holding arms at 90 degrees, the excess skin from the upper arm hangs substantially below what a plastic surgeon would consider normal.
- Other areas (thighs, trunk, back) that show similar degrees of severity to those described above may also be considered
Excess skin removal surgery versus cosmetic surgery
Excess skin removal surgery is not cosmetic surgery. The primary aim of reconstructive excess skin removal surgery is to remove abnormal skin. Cosmetic surgery goes a step further, enhancing normal appearance according to the patient’s preferences.
If you are eligible for excess skin removal surgery but also wish to further enhance your appearance, surgeons can perform cosmetic enhancements for an additional cost.
Check with your health plan to see what’s covered for you.
Even if you follow all the recommendations, it’s realistic to expect that you will still have some excess skin after surgery. For some people, this is totally fine, but it may really bother others. If you do not have abnormal excess skin but wish to explore options that will reshape normal skin or remove fat to improve your appearance, cosmetic surgery (often called body contouring surgery) may be an option for you.
Important things to know
- Wait until your weight stabilizes. For the best results, you should wait until your weight stabilizes at your new size for several months (usually about 18 months after surgery). Otherwise, as you continue to lose weight, you are likely to develop more excess skin. Your weight should be stable for at least 6 months before you consider body contouring surgery.
- Recovery can be painful. Many people who have had body contouring surgery say that the recovery is worse than from metabolic and bariatric surgery. In some cases, you may have to be off work for a month or more to recover fully.
