MedDRA preferred term · a low blood level of the medicine

Drug level decreased: adverse event reports recording this term

9,999 reports to FDA record it, 2004–2026; 0.1% of the database.

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.

9,999
reports recording the term: 0.1% of all reports; 517
reports, 12 months to June 2026: 617 in the 12 months before; 81.2%
marked serious by the reporter: 57.4% across all reports; 2.3%
record death among outcomes, as reported: 9.1% across all reports

9,999 reports in FDA's adverse event database record the MedDRA term "Drug level decreased" (in plain words, a low blood level of the medicine): 0.1% of all reports received between January 2004 and June 2026. Coders pick the term that best matches the reporter's description.

517 reports recorded it in the 12 months to June 2026, down 16% from 617 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Of reports recording this term, 81.2% are marked serious, 2.3% include death among the outcomes and 29% include hospitalisation, as reported.

The drugs listed most often as suspect products in those reports are Inflectra, Humira and Infliximab. That order mostly follows how many reports each drug has overall; the table also gives the term's share within each drug's own reports. FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event."

Reports by month, five years

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

Drugs listed as suspect products in these reports

Drug	Class	Reports with this term	Share of the drug's own reports
Inflectra	Tumor necrosis factor blocker	1,225	4.8%
Humira	—	1,137	0.2%
Infliximab	Tumor necrosis factor blocker	974	1.9%
Vedolizumab	Integrin receptor antagonist	778	1.3%
Remicade	Tumor necrosis factor blocker	692	0.4%
Tacrolimus	Calcineurin inhibitor immunosuppressant	322	0.3%
Stelara	Interleukin-12 antagonist	317	0.4%
Entyvio	Integrin receptor antagonist	215	0.9%
Dilantin	Anti-epileptic agent	189	2.4%
Depakote	Anti-epileptic agent	184	1.3%
Lamotrigine	Anti-epileptic agent	164	0.4%
Voriconazole	Azole antifungal	160	1.2%
Carbamazepine	Mood stabilizer	156	0.7%
Phenytoin	Anti-epileptic agent	142	1.1%
Levetiracetam	—	139	0.3%
Rifampicin	—	126	2%
Afinitor	Kinase inhibitor	125	0.4%
Valproic acid	Anti-epileptic agent	122	0.6%
Lamictal	Anti-epileptic agent	113	0.3%
Adalimumab	Tumor necrosis factor blocker	108	0.3%
Prednisone	Corticosteroid	108	0.1%
Clozapine	Atypical antipsychotic	102	0.1%
Rifampin	Rifamycin antibacterial	101	1.1%
Mycophenolate mofetil	Antimetabolite immunosuppressant	99	0.1%
Cyclosporine	Calcineurin inhibitor immunosuppressant	87	0.2%

Drugs with a page on this site, ordered by the number of their reports recording this term. The last column is the term's share within that drug's own reports, against 0.1% across the whole database. 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."

By pharmacologic class

Class	Reports with this term	Share of class reports	Median drug in class
Tumor necrosis factor blocker	3,115	0.3%	0.1%
Anti-epileptic agent	1,175	0.4%	0.3%
Integrin receptor antagonist	993	0.4%	0.5%
Calcineurin inhibitor immunosuppressant	538	0.3%	0.2%
Atypical antipsychotic	384	0.1%	0%
Azole antifungal	345	0.5%	0.1%
Interleukin-12 antagonist	345	0.4%	0.4%
Kinase inhibitor	280	0%	0%
Mood stabilizer	273	0.5%	0.4%
Corticosteroid	237	0%	0%

Classes ordered by count. Class shares follow the class's overall report volume as much as anything else.

Patients in these reports

Patient age

Under 20.5%52

2 to 114%397

12 to 175.3%525

18 to 4422.5%2,246

45 to 6418%1,800

65 to 746.9%692

75 and over3.7%374

Age not given39.1%3,913

Patient sex

Female38%3,802

Male39.4%3,940

Not given22.6%2,257

Grey bar: all 20,646,523 reports in the database. 36.3% of these reports give the United States as the country.

Questions about "Drug level decreased"

What does "Drug level decreased" mean in an adverse event report?

In plain language: a low blood level of the medicine. It is a MedDRA preferred term, the dictionary FDA uses to code what a reporter described. The report's own description is not published by openFDA and is not shown here.

How many reports record drug level decreased?

9,999 reports through June 2026 (0.1% of all reports), 517 of them in the latest 12 months.

Which drugs appear most often in these reports?

Inflectra (1,225), Humira (1,137), Infliximab (974), Vedolizumab (778) and Remicade (692). Drugs with many reports overall lead almost every term's list. 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."

Does a drug appearing here mean it was responsible for this reaction?

No. FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event."

I have this symptom. What should I do?

This site cannot assess anyone. A pharmacist or clinician can; for an emergency, call the local emergency number. Nothing on this page is medical advice.

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. Terms are pooled across spelling and capitalisation variants of one MedDRA preferred term. 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.