Medications to Avoid after Gastric Bypass & Gastric Sleeve Surgery

Medications to Avoid after Gastric Bypass

Which medications to avoid after Gastric Bypass and Gastric sleeve? Actually, there are no absolute contraindications to any medicines after gastric bypass and gastric sleeve surgery.

However, in the immediate postoperative period, a person may be at risk of bleeding and infections.

Medications that can increase the risk of bleeding or infections should be avoided in the first two to four weeks of the postoperative surgery period.

Secondly, some medications might cause weight gain. Since weight gain is the least desired side effect a person might want to have after gastric bypass surgery, medications that might make you fat should also be avoided.



Medications to Avoid after Gastric Bypass and Gastric Sleeve in the First 2 – 4 Weeks:

During the first two to four weeks, the wound is fresh and the chances of infections and bleeding at the anastomosis site are high.

Medications that might cause bleeding at the surgical site include:

  • NSAIDs:

NSAIDs (Non-steroidal anti-inflammatory drugs) have the potential to cause gastric ulcers. Secondly, they also impair clotting.

The risk of GI bleeding and bleeding at the anastomosis site is high. Hence, NSAIDs should be avoided.

  • Common NSAIDs include:
    • Aspirin or salicylates-containing medicines like Bismol (Bismuth Subsalicylate and other Pepto-Bismol products)
    • Celebrex (Celecoxib)
    • Ibuprofen
    • Naproxen (Aleve)
    • Diclofenac and Aceclofenac
  • What are alternative medicines for pain relief?

Alternative medications for pain relief include Tylenol (Acetaminophen), codeine, and tramadol.

Tylenol (Acetaminophen) is the best pain medicine after gastric sleeve and gastric bypass surgeries.

Topical medications and non-medical options like Yoga are also better options.



  • Blood thinners:

Blood thinners should not be used, for obvious reasons, during the immediate postoperative period.

These include Warfarin, Heparin, Enoxaparin, Xarelto (Rivaroxaban), Eliquis (Apixaban), and others. Usually, patients get off the bed within 3 days but in situations where bed stay is more than 3 days, prophylactic anticoagulation is recommended to avoid blood clots.

  • How to manage and prevent blood clots?

If you have clots in your legs or have developed pulmonary embolism, you can not avoid blood thinners. Rather blood thinners can be life-saving.

Your doctor is the best judge to advise you on a blood thinner in consultation with a hematologist.

However, it is best to keep ambulated after surgery so as to not develop any clots in the first place. Tedd Stocking (compression stockings) can be worn during the first few days if you are not mobile for 3 days or more.



  • Antibiotics to avoid after gastric bypass and gastric sleeve surgery:

Antibiotics are prescribed by most surgeons for a short period of time after surgery, however, prolonged use of antibiotics is not advisable.

Prolonged use of antibiotics may cause pseudomembranous colitis or other superinfections like fungal infections and resistant bacterial infections.

If indicated, antibiotics should be used in consultation with an infectious disease specialist. However, one should avoid broad-spectrum antibiotics which may increase the chances of superinfections.

Other antibiotics to avoid after gastric bypass and gastric sleeve surgery include:

  • Aminoglycosides (Amikacin and Gentamicin): These antibiotics increase the risk of kidney failure
  • Tetracyclines (Vibramycin): These antibiotics can cause gastric ulcers or “pill ulcers” when they are in contact for a long time with the gastric mucosa.

Most oral antibiotics which can cause severe gastric upset including amoxicillin, fluoroquinolones, and oral cephalosporins. The absorption of oral antibiotics, oral macrolides, and beta-lactams in particular may also be unpredictable and should not be used [Ref].

  • How to Manage Infections in the Immediate Post-operative Periods and Which Antibiotics to Use?

Take antibiotics for a short period after surgery as advised by your surgeon. In case, you develop any infection, you should consult your doctor and an infectious disease specialist.

Preferred antibiotics after gastric bypass and gastric sleeve surgery depend on the site involved. These include [Ref]:

Antibiotics for Bariatric Surgical Prophylaxis

First-Line Antibiotics

Second-Line Antibiotics

For Penicillin Allergic Patients

Gastroduodenal Site InvolvementCefazolinCefotaxime or CeftriaxoneClindamycin + Ciprofloxacin
Ileal InvolvementCefoxitin or

Cefazolin + Metronidazole

Cefotaxime + Metronidazole, or

Ceftriaxone + Metronidazole

Moxifloxacin + Metronidazole


  • Supplements and Herbal medicines:

Avoid supplements in the immediate postsurgical period. Supplements might worsen your gastrointestinal symptoms, make you feel like throwing up, and increase abdominal pain if you take them immediately after surgery.

These include:

  • Iron
  • Calcium
  • Magnesium
  • Zinc

Some herbal medicines might make your blood thin and increase the chances of bleeding. These include:

  • Turmeric acid
  • Gink biloba
  • Peppermint
  • Fenugreek
  • Milk Thistle

Which Vitamins Are Safe and How to Take Them?

Severe deficiency of a vitamin such as iron deficiency is best treated by parenteral iron or blood transfusions in case the hemoglobin is very low.

Multivitamins are usually started a few weeks before gastric bypass and gastric sleeve surgery to avoid deficiency after the surgery.

In cases where patients do need vitamins in the immediate post-operative period, it is best to use parenteral supplements such as injectable Neurobion or sublingual folic acid and vitamin B12.

Most bariatric clinics advise vitamins in solution or liquid forms for better digestion. Oral capsules and tablets may be started after a month of the bariatric surgical procedure.

However, unless your doctor has advised you to take vitamins or supplements, you should not take them in the first 2 to 4 weeks.



  • Corticosteroids after Bariatric Surgery:

Corticosteroids impair wound healing, cause hyperglycemia, and impair immunity. Patients who use corticosteroids are at an increased risk of superinfections.

In addition, they have delayed wound healing and hernia formation at the site of entry.

  • How to manage?

Corticosteroids should be avoided unless you have life-threatening asthma or other allergic condition for which corticosteroids are a must.

In addition, patients on long-term corticosteroids should be given intravenous hydrocortisone during and immediately after the surgery so as to avoid adrenal crisis.

However, keep the duration and the dose to the minimum possible so as to avoid complications after surgery.



  • Oral Contraceptives after Gastric Sleeve and Gastric Bypass:

It is better to avoid hormonal contraceptives as these pills increase the chances of clotting in the immediate postoperative period.

An intrauterine device such as Mirena and Nexplanon is advised by most doctors after surgery for the first 12 to 18 months.

OCPs are least preferred as the stomach is not friendly to absorbing and digesting food and medicines.

Secondly, the absorption of most medications is impaired after gastric bypass surgery.



  • Diabetes Medications During and After Gastric Bypass and Gastric Sleeve Surgery:

Most bariatric surgical procedures are associated with significant improvement in blood glucose.

The risk of hypoglycemia is multiplied if you are taking the following diabetes medications:

  • Insulin
  • Sulfonylureas (Glyburide, Glimepiride, Glipizide, and Gliclazide)
  • Meglitinides (Repaglinide and Nateglinide)

Other diabetes medications may worsen gastrointestinal symptoms. These include:

  • Metformin (Glucophage)
  • Acarbose (Glucobay)
  • DPP-IV inhibitors like Sitagliptin (Januvia) and Vildagliptin (Galvus)
  • GLP-1 analogs (Ozmepic, Trulicity, and Victoza)

The risk of developing gallstones increases with the following diabetes medications:

In addition, SGLT-2 inhibitors such as Jardiance (Empagliflozin) and Farxiga (Dapagliflozin) may increase the risk of dehydration and renal failure.

  • How to Manage Diabetes after Gastric Bypass and Gastric Sleeve Surgery?

Your doctor may stop or reduce the dose of insulin or other oral antidiabetic medications. Metformin is a safe alternative and does not cause hypoglycemia.

However, it may be associated with gastrointestinal side effects like abdominal pain, bloating, nausea, and vomiting.

Short-acting and rapid-acting insulin (Insulin Aspart, Glulisine, and Lispro) are the best to use during the immediate post-surgery period and until the wound has healed.

For patients who wish to boost their weight loss struggle and are able to tolerate can use Ozempic, Rybelsus, or Mounjaro, in addition to Jardiance, Farxiga, or metformin a few weeks later after the surgery.



Medications Associated with Weight Gain:

Certain medications can increase your appetite and cause weight gain. Avoid, unless necessary, those medications that make you fat.

Common medications that are associated with weight gain include:

  • Antidepressants (Tricyclic antidepressants and Paroxetine)
  • Antihistamines
  • Antipsychotics (Olanzapine)
  • Mood stabilizers (Sodium valproate)
  • Corticosteroids (Prednisolone)

How to manage?

  • Alternative medicines are usually available, however, it is recommended to consult your doctor first.
  • The atypical antidepressant, Bupropion, is associated with the least weight gain. Rather it may cause weight loss.
  • Novel antipsychotics like Ziprazadone (Geodon) and Lurasidone (Latuda) are associated with less weight gain.

Bariatric Surgery and the Effect of Drug Absorption:

Bariatric surgery, especially malabsorptive surgeries like Roux En Y Gastric Bypass Surgery, affects the absorption of most oral drugs.

The absorption of drugs and food is impaired because of the following reasons:

  • A short area for absorption, as a part of the proximal Jejunum, is resected
  • Impaired mixing of stomach acid may affect the absorption of drugs that require an acidic environment or medicines that have a PH-dependent absorption
  • Impaired mixing of bile acids with the drugs that may impair the absorption of drugs that require bile acids for better absorption such as levothyroxine, cyclosporin, tacrolimus, and phenytoin.
  • Bacterial overgrowth may occur in some patients because the food may not be adequately propelled in some areas of surgical anastomosis.

In addition, patients may develop severe gastrointestinal side effects with some of the drugs.

These include drugs that cause stomach ulcers like aspirin and salicylates and NSAIDs (non-steroidal painkillers).

The table below shows the effect of Bariatric Surgical Procedures on the absorption of various drugs:

Systemic exposure to drugs after Gastric Bypass Surgery

Systemic exposure increased

Systemic exposure decreased

Ethanol (Alcohol)Tamoxifen
Vitamin B 12


Psychiatric Medications After Gastric Bypass:

It is logical that some of the effects of psychiatric medications may be blunted in part because of the impaired absorption of the drugs.

Patients who undergo a bariatric surgical procedure are at an increased risk of depression and suicide.

This could be somewhat related to the change in the pharmacokinetics of psychiatric medications.

Sertraline (Zoloft) is a commonly prescribed antidepressant that has been studied in patients who have had a bariatric surgical procedure. The absorption is impaired to a great extent in patients who have had a bariatric surgical procedure

In one study, there was no change in the absorption of psychiatric medications.

The following drugs were studied and had similar rates of absorption as those who did not have gastric bypass surgery:

Patients who are on antidepressants must continue these and get a psychiatric consult for dose adjustment or a change in the formulation (syrups or solutions) so that the change in absorption may not affect drug exposure.



Best antidepressant After Gastric Bypass Surgery:

If you have undergone a bariatric surgical procedure, it is for sure that you are obese. All antidepressants are associated with weight gain except for a few.

Since you don’t want to gain weight, it is best that you take Bupropion (Wellbutrin). Bupropion (Wellbutrin) in combination with Naltrexone is an FDA-approved drug for the treatment of obesity.

Bupropion seems a rational first-line drug if you are not on any antidepressant. However, it is recommended to continue the same antidepressant that you have been using before the bariatric surgery.

Although bupropion does not cause weight gain, it may not be as effective as other potent antidepressants.


Best Antacid after Gastric Sleeve:

The Rapid-acting antacids like Tums, Gaviscon, and Mucaine that contain calcium carbonate or Pepto-Bismol and Sucralfate are the best to relieve heartburn immediately.

However, PPIs like Omeprazole (Prilosec), Esomeprazole (Nexium), Lansoprazole, and Pantoprazole are the most potent medicines that suppress stomach acid and relieve symptoms of heartburn and GERD.

Can you use weight loss medications like Saxenda and Ozempic after Gastric bypass or Gastric sleeve surgery?

Yes. You can use Saxenda, Wegovy, Ozempic, or Mounjaro after gastric bypass surgery. However, with gastric bypass or other bariatric surgical procedures, you already have lost enough weight that you won’t need a weight loss pill (Cntrave or Qsymia) or injection to lose weight.

Secondly, GLP-1 analogs like Ozempic and Saxenda may worsen your gastrointestinal symptoms, and double your risk of developing gallstones and pancreatitis.

In rare cases, after 5 to 10 years, weight loss pills like Qsymia and Contrave or weight loss injections like Saxenda and Wegovy/ Ozempic may be used to limit the weight regain.



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Written by Dr. Ahmed

I am Dr. Ahmed (MBBS; FCPS Medicine), an Internist and a practicing physician. I am in the medical field for over fifteen years working in one of the busiest hospitals and writing medical posts for over 5 years.

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