Pharmacologic class (EPC) · 2 drug pages

Tryptophan hydroxylase inhibitor: adverse event reports filed with FDA

5,637 reports list a drug in this class as a suspect or interacting product, 2017–2026.

Read first · FDA's statement on these data

Adverse event reports submitted to FDA do not undergo extensive validation or verification. Therefore, a causal relationship cannot be established between product and reactions listed in a report. While a suspected relationship may exist, it is not medically validated and should not be the sole source of information for clinical decision making or other assumptions about the safety or efficacy of a product. Additionally, it is important to remember that adverse event reports represent a small percentage of total usage numbers of a product. Common products may have a higher number of adverse events due to the higher total number of people using the product. openFDA, FDA

FDA adds: "There is no certainty that the reported event (adverse event or medication error) was actually due to the product. FDA does not require that a causal relationship between a product and event be proven, and reports do not always contain enough detail to properly evaluate an event." The information in these reports "cannot be used to estimate the incidence of these events."

Do not rely on openFDA to make decisions regarding medical care. While we make every effort to ensure that data is accurate, you should assume all results are unvalidated.

Not medical advice. This site counts what was reported to FDA. Questions about a medicine or device belong with a pharmacist or clinician.

5,637
reports across the class: 0% of all reports; 51
reports, 12 months to June 2026: 51 in the 12 months before; 34.6%
marked serious by the reporter: 57.4% across all reports; 2
drugs with a page: brand and generic names counted separately

Tryptophan hydroxylase inhibitor is a pharmacologic class (an FDA Established Pharmacologic Class) with 2 drug pages on this site. Together those drugs are listed as a suspect or interacting product in 5,637 adverse event reports received by FDA, 0% of the database, from April 2017 to June 2026.

51 reports arrived in the 12 months to June 2026, close to the 51 of the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. 34.6% of the class's reports are marked serious, 6.9% record death among the outcomes and 15.1% record hospitalisation, as reported.

Across the class the reactions recorded most often are diarrhoea (14.3%), nausea (10.8%) and constipation (10.5%). The class median share shown beside each term is the middle value across the member drugs; it is the comparison used on every drug page in this class.

The members table is ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Drugs in the class

Drug	Name type	Reports	Latest 12 months	Marked serious	Top term recorded
Telotristat ethyl	generic	3,700	0	32%	Diarrhoea
XermeloTelotristat ethyl	brand	1,937	51	39.6%	Diarrhoea

Ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Reports by month, five years

FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.

Reactions recorded across the class

share of class reports recording the termmedian drug in the class

Diarrhoealoose or frequent stools14.3%806
Nauseafeeling sick10.8%609
Constipationconstipation10.5%594
Abdominal painstomach or belly pain9.1%513
Off label useused for a purpose or in a way not on the label8.8%496
Fatiguetiredness7%396
Flatulencewind7%392
Flushingsudden reddening or warmth of the skin6.2%347
Deaththe patient died; cause not stated by this term5.7%322
Headachehead pain5.7%322
Drug ineffectivethe medicine did not work as expected5.6%315
Malaisegeneral feeling of being unwell4.4%248
Hospitalisationadmission to hospital4.2%237
Decreased appetitereduced appetite4.1%232
Vomitingbeing sick3.5%197
Abdominal pain upperupper stomach pain3.4%189
Product dose omissiona dose was missed3.1%177
Weight decreasedweight loss3.1%174
Abdominal distensiona bloated abdomen3.1%172
Astheniaweakness or lack of energy3%168
Disease progressionthe disease advanced2.6%144
Defaecation urgency2.5%141
Dizzinesslight-headedness or unsteadiness2.3%129
Product dose omission issuea dose was missed2.1%120
Dehydrationdehydration2.1%116

Solid bar: share of all class reports. Hollow bar: the median share across the 2 member drugs, the reference used on each member's page. One report can record several terms.

Outcomes, patients and reporters

Outcomes recorded

Death6.9%387

Life-threatening0.1%5

Hospitalisation (initial or prolonged)15.1%853

Disability0%0

Congenital anomaly0%0

Other serious18.8%1,060

Not serious65.4%3,685

Patient age

Under 20%0

2 to 110%0

12 to 170%0

18 to 441.6%93

45 to 6415.9%898

65 to 7414.2%802

75 and over9.9%557

Age not given58.3%3,287

Who reported

Physician11.6%652

Pharmacist0.9%48

Other health professional4.6%258

Lawyer0%0

Consumer or non-health professional81.4%4,591

Not given1.6%88

Grey bar: all 20,646,523 reports in the database. Outcome flags are as the reporter set them and are not verified by FDA.

Questions about Tryptophan hydroxylase inhibitor reports

Which drugs are in the Tryptophan hydroxylase inhibitor class on this site?

Telotristat ethyl and Xermelo. Class membership comes from the pharmacologic class (EPC) on the drug's FDA label.

How many reports does the class have?

5,637 reports through June 2026, 51 of them in the latest 12 months. A report listing two drugs of the class counts once for each.

What reactions are recorded most often?

diarrhoea (14.3%), nausea (10.8%), constipation (10.5%), abdominal pain (9.1%) and off label use (8.8%).

Can the members table be used to rank the drugs?

No. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic." Drugs differ in how many people take them, in the conditions they treat, in time on the market and in how diligently reports are collected.

How do I report an adverse event?

Through FDA MedWatch (Form FDA 3500, or 1-800-FDA-1088) or to the manufacturer. See the guide on how to report.

Where this comes from. Counts are built from the openFDA Drug Adverse Event (FAERS) bulk export released 28 Sep 2026, which holds reports FDA received through 30 Jun 2026. Drug names are as reported, resolved to the brand or generic name on the FDA label where openFDA's harmonisation matched them; classes are the pharmacologic class (EPC) from the label and the National Drug Code Directory of 17 Sep 2026. A class is the Established Pharmacologic Class most often attached to a drug's reports by openFDA's label harmonisation, or from the NDC Directory where reports carry none. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.

Drug data (FAERS) through 30 Jun 2026; device data (MAUDE) through 31 Aug 2026. Not medical advice.