Disclaimer: None of the information in this article constitutes medical advice, and is just the opinion of the writer(s) and published for informational purposes only. We recommend that patients follow their doctor’s guidance in regard to prescription medication.
Linzess is the most popular prescription medication for Irritable Bowel Syndrome (IBS). The manufacturer claims it can help patients have more frequent and complete bowel movements, and reduce discomforting IBS symptoms such as stomach pain and bloating.
In this article we’ll review the medical studies on Linzess to determine whether we believe it’s likely to be safe and effective for improving IBS symptoms. We’ll also highlight side effects of the medication.
The generic form of Linzess is called linaclotide, and we will use these terms interchangeably throughout the article as they refer to the same active drug.
Does Linzess Work?
Linzess is typically prescribed for IBS-C, which indicates IBS with constipation. The other form of IBS is IBS-D, or IBS with diarrhea.
A 2012 clinical trial published in the American Journal of Gastroenterology evaluated the efficacy of Linzess for treating IBS-C. Patients either took Linzess or a placebo pill daily for 26 weeks.
Linzess was found to be effective, reducing average scores for abdominal pain, abdominal bloating and bowel symptoms such as straining while passing stool. Gastrointestinal pain was reduced by 14.4% in the Linzess group compared to the placebo group.
A more recent medical study conducted in Germany tested the effects of the drug on patients diagnosed with IBS-C. Rates of abdominal pain and bloating intensity reduced by around 50% for patients taking Linzess, and the researchers concluded that the drug is effective in improving major symptoms of IBS-C.
A medical review of Linzess, which analyzed results from 25 individual clinical trials, found the medication to be not only effective for managing IBS-C but also for managing chronic constipation. Patients with chronic constipation reported more frequent and normalized bowel movements while taking Linzess, and also reported reduced abdominal pain to a statistically significant degree.
We can conclude from the medical data that Linzess is likely to be effective for managing symptoms of IBS-C and chronic constipation. This doesn’t mean it will work for all patients; just that it works on average.
How Does Linzess Work?
Linzess is a peptide composed of 14 individual amino acids. It’s minimally absorbed by the body, and increases intestinal fluid secretion which causes improved intestinal transit.
The term “bloating” typically refers to a feeling of fullness in the stomach and is often associated with delayed gastric emptying and delayed intestinal motility, so Linzess can resolve this in some patients.
Put simply, many patients with IBS-C or chronic constipation don’t move food from their stomach through their intestines at a normal rate, and Linzess can speed up the rate of food processing to normalize it and reduce symptoms.
The medical review linked in the previous section documented how Linzess was not found to impact human metabolism, and that neither the drug nor its active metabolite were found in blood samples, which suggests that Linzess functions entirely in the intestinal tract and then is excreted.
Linzess Side Effects
Because Linzess increases intestinal motility and fluid secretion, the most common side effect is diarrhea. This is also why the drug is typically prescribed to IBS-C but not IBS-D patients.
One medical study found that upwards of 20% of patients on Linzess experienced regular diarrhea.
Another medical review examined the side effects experienced by Linzess patients, and noted increased rates of flatulence (gas). According to the linked study, 7.9% of Linzess patients had to discontinue medical trials due to uncomfortable side effects, compared with only 2.8% of patients taking placebo.
Linzess also carries a black box warning label as required by the Food and Drug Administration (FDA) in the U.S., which is used for medications that can cause serious side effects or death. The black box warning indicates that the drug can cause severe dehydration in pediatric patients, and that its safety is unclear for patients under the age of 18.
Given that there is no warning for adult patients, it seems logical to avoid use of this drug in children or adolescents.
Linzess is sold at three separate dosages: 72 micrograms (mcg), 145 mcg and 290 mcg.
All of the medical trials we’ve reviewed for IBS-C have used the dosage of 290 mcg, while the FDA approves Linzess for chronic constipation at a lower dose of 145 mcg.
A more recent medical trial conducted in Japan found that Linzess was effective for constipation at a dose of 0.5 milligrams (mg), which is around 3x the dosage that’s currently approved in the U.S. for constipation.
We don’t recommend any off-label use of this medication, but it’s worth noting emerging research that may lead to improved effectiveness. If more studies are published showing the safety and efficacy of Linzess at 0.5 mg, it may be approved for use in the U.S. at that dosage.
Should I Take Linzess Generic?
The generic form of Linzess is called linaclotide. Both drugs contain the exact same active ingredient.
There should be no difference in effectiveness of generic versus branded medications, since they contain the same active ingredient and inactive ingredients (like colorants) don’t affect treatment.
A medical review from 2019 confirmed this: generic drugs are just as effective as their branded counterparts on average.
We typically recommend that patients speak to their doctor about generic drugs instead of the branded version, especially if the patient is on a low or moderate income, because generic drugs are often significantly cheaper. For patients paying out-of-pocket, switching from a brand-name drug to a generic version can sometimes save thousands of dollars per year.
Linzess Vs. Trulance
Another popular IBS-C and chronic constipation medication is called Trulance, and many patients express interest about which drug is more effective.
An extensive medical review published in the American Journal of Gastroenterology compared data on the two drugs, analyzing results from over 10,000 patients.
The study authors found that both drugs were similarly effective and had similar side effect profiles; there was no statistically significant difference between treatment with either drug.
This is unsurprising given that both drugs are guanylate cyclase-c agonists, meaning they have the same biological mechanism of action.
Given that the drugs are similarly effective, we believe that it makes sense for patients to consider whichever drug is the cheaper option for them.
Linzess Vs. Amitiza
An older-generation IBS medication called Amitiza has also been studied in comparison with Linzess.
A medical review compared the two medications (amongst other IBS drugs), and found that Linzess was more effective overall, across multiple endpoints. It’s common for newer drugs to be more effective due to enhanced research and development, so this result is unsurprising.
The review did note that Amitiza caused significantly fewer events of diarrhea, which means it may be a more effective option for IBS-D.
How Long Does It Take For Linzess To Work?
The Linzess website claims that the medication is likely to work within the first week, and that does appear to be accurate based on medical research.
One of the previously-linked trials we covered in the efficacy section includes a graph (which we can’t post here for copyright purposes) detailing symptom relief over time. Linzess patients experienced around a 10% decrease in pain in the first week, and the pain scores continued to drop throughout the trial.
This means it might only take a few days for Linzess to have some beneficial effect, but its most significant effect will be experienced after months of continued use.