Frequently Asked Questions

What products can be used to unclog feeding tubes?



Tube occlusion is a common complication of enteral feeding tubes, which can be caused by high protein or viscous feeding formula, medications, improper flushing technique, small lumen tubing, or a combination of factors.  In most cases, this obstruction will result in delayed administration of medications and nutrition. If not corrected, the patient may require additional surgical intervention to replace tubes, which is associated with increased costs and trauma to the patient. Severe tube occlusions have also resulted in tearing of the tube and direct administration of feeds to the esophagus and possible formation of esophageal bezoars.1-3

 Prevention is the preferred solution to this common problem.  If possible, elixir and solution forms of medications should be used.4  If not commercially available, appropriate formulations can be compounded as long as all medications are adequately crushed and/or dissolved.  Refer to your pharmacy policy and procedure, or resources such as Drug Topics Red Book, Lexicomp’s Drug Information Handbook, and/or the Pharmacist’s Letter for a list of medications that cannot be crushed or opened.  These lists will primarily include any medication that is time-released and/or enteric-coated.  

 If an appropriate oral formulation is not available, consider an alternative to enteral administration.4  While more invasive and/or potentially costly, many drugs can be given by other routes such as parenteral, transdermal, sublingual, inhaled, or rectal.  Additionally, flushing of the tubing has been established as an effective preventative measure.  Tubes should be flushed with at least 30 mL of sterile water with every bolus feed and before and after medication administration.4,5 If using continuous feeds, flushing should occur every 4 hours to maintain patency.5  Even when these preventative measures are taken, tube occlusion can occur at a rate as high as 15%.4,6  Finally, the formula used as a feeding solution should be evaluated for protein and fiber content, and overall viscosity and the diameter of the tube lumen should be considered in order to maximize flow rate.

 The use of pancreatic enzyme and sodium bicarbonate solutions has been shown to be effective in the prevention and treatment of clogged enteral feeding tubes, and in many institutions this had become common practice.7  The studies evaluating this method used the pancrelipase brand Viokase with sodium bicarbonate to reach optimal pH.  The solution was then injected into the tube, clamped, and flushed.4  In 2004, due to concerns about consistency, safety, and effectiveness of pancreatic enzyme products, it was mandated that all products must meet standard formulation guidelines and undergo clinical trials to obtain Food and Drug Administration (FDA) approval.8  Only 3 brands of enzymes, Pancreaze, Creon, and Zenpep, fulfilled these requirement and received approval.  These are the only preparations currently marketed in the United States. Unfortunately, these products are now produced as delayed-release capsule dosage forms, whereas Viokase was produced as powder or crushable tablet. Therefore, due to the reformulation of the products, results of prior clinical studies cannot be directly applied.  There is no information to support similar efficacy of the new preparations for use in clogged feeding tubes; furthermore, the new release characteristics of the products are not likely conducive to instillation in the feeding tube.

 Although, the appropriate course of action to manage a clogged feeding tube has not been universally established there are studies, some of which will be discussed below, that can help guide treatment options.


Literature review

Several irrigants including carbonated soda, cranberry juice, and water have been studied to resolve an existing clog.  In a study of 30 male patients receiving continuous nasogastric small bore tube feeds, subjects were randomized to receive irrigations with either 30 mL of water or cranberry juice every 4 hours.Of the 15 tubes irrigated with water, none occluded.  However, 73.3% (11/15) of the tubes irrigated with cranberry juice were occluded, and the remaining 4 were discontinued from the study for various reasons.  This difference in occlusion rates was statistically significant in favor of water when considering the mean duration of tube use (403.5 hours with water vs. 130.1 hours for cranberry juice, p<0.001).  These results were later confirmed in a in vitro study of 108 feeding tubes irrigated with water, Coca-Cola, or water over 3 days.10  The effectiveness of water was shown to be similar to Coca-Cola, and cranberry juice was consistently inferior to both.  Although water and Coca-Cola were similar, the authors recommended that water be considered the first-line irrigant based on cost and accessibility. The American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.) Practice Recommendations also consider water as the preferred irrigant due to proven efficacy, easy accessibility, and low cost.5 Overall, use of acidic beverages such as cola or cranberry juice is considered controversial in that such beverages may denature proteins within the feeding formula, therefore contributing to clogging.4,9

 In one study, 9 substances (Pancrease, Viokase, pork pancreatin, bromelain, papain, cranberry juice, chymotrypsin, and distilled water) were evaluated in 3 feeding tubes each to determine their ability to resolve a clog after 4 hours.11 The methods of this study conducted in the laboratory involved an isotonic nutrition formula injected into 41 feeding tubes.  The tubes were incubated until they clogged; the tubes clogged within 7 days.  Once the clogs formed, each substance listed above was used in an attempt to clear the clog by injecting 1 mL of the substance into the clogged tube.  The investigators attempted to flush the tubes every 30 minutes after the substances were injected.  If the flush attempt was unsuccessful, another 1 mL of the substance was injected into the clogged tube.  This was repeated until the tube could be irrigated or 4 hours elapsed. None of these substances declogged the feeding tubes within the 4-hour period; however, the chymotrypsin and papain substances were most effective.  Both substances resulted in movement of the clog.  Since papain is often found in meat tenderizer it is easily accessible and was therefore considered a viable option.

 Another in vitro study evaluated the ability of 6 solutions to resolve an occlusion: Adolf’s meat tenderizer (papain), Viokase (trypsin, chymotrypsin, amylase and lipase), Sprite, Pepsi, Coca-Cola, or Mountain Dew.7  The investigators formed a clot and then transferred the clot to the solutions mentioned above in an attempt to dissolve the clot.  Unlike the previous study, the authors reported the pH of each mixture.  They adjusted Viokase, using sodium bicarbonate, to a level of 7.9 and adjusted the pH of papain to a level of 6.5.  The results of this study showed that the Viokase pH 7.9 was significantly better than the other products (p<0.01), while Viokase pH 5.9 and papain were the lowest scoring products.  In order to determine if the pH or Viokase was responsible for the significant effects, the investigators compared the Viokase results to distilled water adjusted to the same pH (7.9).  Viokase was superior to pH adjusted distilled water, leading the authors to speculate that Viokase itself and not the pH was responsible for the efficacy.  Applying the results of their in vitro study, the authors used Viokase pH 7.9 to attempt to clear 10 patients’ clogged feeding tubes.  Five tubes were cleared with 1 attempt with 2 more becoming clear with the second attempt.  Three tubes could not be cleared.  These results suggest that Viokase pH 7.9 was the most effective solution for clearing a clogged feeding tube and that papain, or meat tenderizer, may not be as effective as previously reported.


Commercially available products

Clog Zapper is a commercially available product, which has also shown efficacy in clearing occlusions.4,12  This system includes a syringe filled with powder consisting of papain and a variety of enzymes that is then reconstituted with water and instilled into the clogged tube through a catheter.  The solution is then allowed to dwell for 30 to 60 minutes before being flushed with water.   A company study of 17 occluded tubes showed Clog Zapper to be successful in clearing formula-related clots with the first or second attempt. While effective, this product does have a high cost and has not been studied for drug- related occlusions.   

 Other commercially available products have been designed to mechanically dismantle clogs and may be used regardless of the cause of the clog.  Bard offers the “PEG cleaning brush” which is a flexible catheter with a feather cut brush at the distal end meant to scrape and break up the clog.13 The brush prevents perforation that may occur with exposed wires.  Bionix has developed the “Enteral Feeding Tube Declogger”, a polypropylene flexible rod, which when inserted and rotated into the feeding tube dislodges the obstruction.14  These products are designed for single-use only, making cost a limitation to use.  However, Bionix does offer a Medicare reimbursement code protocol which may improve cost effectiveness.

 If all of these agents fail, a gastroenterologist and/or surgeon should be consulted to evaluate the patient for replacement of the feeding tube.



The reformulation of pancreatic enzymes has presented clinicians with a dilemma in that Viokase, a product with demonstrated efficacy in clearing clogged feeding tubes, is no longer on the market.  Overall, prevention appears to be the key factor in the management of enteral feeding tube occlusion.  At least 30 mL of sterile water flushes should be used every 4 hours or before and after tube feeds and medications. To prevent tube clogging due to medication administration, it is recommended to chose alternate formulations of medications or routes of administration whenever possible.

 If an occlusion does occur, sterile water should be used first due to proven efficacy, low cost, and a favorable adverse effect profile.  Use of beverages, such as carbonated soda and cranberry juice, are not recommended due risk of worsening the clog and lack of evidence of efficacy.  Papain as a sole irrigant has produced varying results. However, the commercially available Clog Zapper, which contains papain along with digestive enzymes, has shown some efficacy in unpublished company research.  Other commercial agents, such as the Bard PEG cleaning brush or Bionix Enteral Feeding Tube Declogger, are designed to mechanically dismantle clogs, and can be used for formula or medication-related occlusions. If the clog is not resolved by these methods, it is recommended to change the feeding tube.



  1. Cremer AS, Gelfand DW. Esophageal bezoar resulting from enteral feedings. JPEN J Parenter Enteral Nutr. 1996;20(5):371-373.
  2. Garcia-Luna PP. Esophageal obstruction by solidification of the enteral feed: a complication to be prevented. Intensive Care Med. 1997;23(7):790-792.
  3. Irgau I, Fulda GJ. Esophageal obstruction secondary to concretions of tube-feeding formula. Crit Care Med. 1995;23(1):208-210.
  4. Beckwith MC, Feddema SS, Barton RG, Graves C. A guide to drug therapy in patients with enteral feeding tubes: dosage form selection and administration methods. Hosp Pharm. 2004;39(3):225-237.
  5. Bankhead R, Boullata J, Brantley S, et al. A.S.P.E.N. Enteral nutrition practice recommendations. JPEN J Parenter Enteral Nutr. 2009;33(2):122-167.
  6. Pancorbo-Hidalgo PL, Garcia-Fernandez FP, Ramirez-Perez C.  Complications associated with enteral nutrition by nasogastric tube in an internal medicine unit.  J Clin Nurs. 2001;10(4):482-490. 
  7. Marcuard SP, Stegall KL, Trogdon S. Clearing obstructed feeding tubes. JPEN J Parenter Enteral Nutr. 1989;13(1):81-83.
  8. Food and Drug Administration. Guidance for industry exocrine pancreatic insufficiency drug products – submitting NDAs.  Accessed June 12, 2010.
  9. Wilson MF, Haynes-Johnson V. Cranberry juice or water? A comparison of feeding-tube irrigants. Nutr Support Serv. 1987;7(7):23-24.
  10. Metheny NA, Eisenberg P, McSweeney M. Effect of feeding tube properties and three irrigants on clogging rates. Nurs Res. 1988;37(3):165-169.
  11. Nicholson LJ. Declogging small-bore feeding tubes. JPEN Journal Parenter Enteral Nutr. 1987;11(6):594-597.
  12. Clog Zapper product information. Wheeling, IL: Corpak Medsystems; 2002.
  13. BARD PEG Cleaning Brush.  Accessed June 13, 2010.
  14. Bionix DeCloggers.  Accessed June 13, 2010.


By Lauren Dandeles, PharmD