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Belviq XR Side Effects

Generic name: lorcaserin

Medically reviewed by Last updated on May 31, 2022.

Note: This document contains side effect information about lorcaserin. Some of the dosage forms listed on this page may not apply to the brand name Belviq XR.

For the Consumer

Applies to lorcaserin: oral tablets


Special Alerts:

[Posted 02/13/2020]

Link to Original MedWatch: [Web]

AUDIENCE: Patient, Health Professional, Pharmacy

ISSUE: FDA has requested that the manufacturer of lorcaserin (Belviq, Belviq XR) voluntarily withdraw the weight-loss drug from the U.S. market because a safety clinical trial shows an increased occurrence of cancer. The drug manufacturer, Eisai Inc,. has submitted a request to voluntarily withdraw the drug.

When FDA approved lorcaserin in 2012, we required the drug manufacturer to conduct a clinical trial to evaluate the risk of cardiovascular problems. A range of cancer types was reported, with several different types of cancers occurring more frequently in the lorcaserin group, including pancreatic, colorectal, and lung.

BACKGROUND: In January 2020, FDA announced we were reviewing clinical trial data and alerted the public about a possible risk of cancer associated with lorcaserin based on preliminary analysis of the data.



Patients should stop taking lorcaserin and talk to your health professionals about alternative weight-loss medicines and weight management programs. It is best to dispose of unused lorcaserin using a drug take back location, available at: [Web], but if you can't get to one you can dispose of lorcaserin in your household trash:

  • Mix the pills with an unappealing substance such as dirt, cat litter, or used coffee grounds; do not crush them.

  • Place the mixture in a container such as a sealed plastic bag.

  • Throw away the container in your trash at home.

  • Remove or delete all personal information on the prescription label of empty medicine bottles or packaging, then throw away or recycle them.

FDA is not recommending special screening for patients who have taken lorcaserin. Talk to your health care professional if you have questions.

Health Professionals

Health professionals should stop prescribing and dispensing lorcaserin to patients. Contact patients currently taking lorcaserin, inform them of the increased occurrence of cancer seen in the clinical trial, and ask them to stop taking the medicine. Discuss alternative weight-loss medicines or strategies with your patients.

FDA is not recommending special screening for patients who have taken lorcaserin. As with any individual patient, regardless of prior lorcaserin treatment, standard screening recommendations for cancer should be implemented.

For more information visit the FDA website at: [Web] and [Web].

Side effects include:

Nondiabetic patients: Headache, dizziness, fatigue, nausea, dry mouth, constipation.

Diabetic patients: Hypoglycemia, headache, back pain, cough, fatigue.

For Healthcare Professionals

Applies to lorcaserin: oral tablet, oral tablet extended release

Nervous system

Very common (10% or more): Headache (up to 16.8%)

Common (1% to 10%): Dizziness, impaired attention/memory

Uncommon (0.1% to 1%): Tremor, confusion, disorientation

Very rare (less than 0.01%): Serotonergic excess

Frequency not reported: Neuroleptic Malignant Syndrome/serotonin syndrome, somnolence[Ref]


Common (1% to 10%): Hypertension

Uncommon (0.1% to 1%): Regurgitant cardiac valvular heart disease, bradycardia[Ref]


Common (1% to 10%): Anxiety, insomnia, stress, depression/mood problems

Uncommon (0.1% to 1%): Euphoria, suicidal ideation

Frequency not reported: Hallucination, dissociation[Ref]


Very common (10% or more): Decreased lymphocyte count (up to 12.2%), decreased hemoglobin (up to 10.4%)

Common (1% to 10%): Decreased red blood cell count, decreased neutrophil count

Uncommon (0.1% to 1%): Decreased white blood cell count[Ref]


Very common (10% or more): Hypoglycemia (up to 29.3%)

Common (1% to 10%): Worsening of diabetes mellitus, elevated prolactin[Ref]


Very common (10% or more): Upper respiratory tract infection (up to 13.7%), nasopharyngitis (up to 13%)

Common (1% to 10%): Cough, oropharyngeal pain, sinus congestion[Ref]


Common (1% to 10%): Fatigue, peripheral edema, chills[Ref]


The most common adverse reactions for non-diabetic patients were headache, dizziness, fatigue, nausea, dry mouth, and constipation. For diabetic patients, the most common adverse reactions were hypoglycemia, headache, back pain, cough, and fatigue.[Ref]


Common (1% to 10%): Rash

Uncommon (0.1% to 1%): Hyperhidrosis[Ref]


Common (1% to 10%): Nausea, diarrhea, constipation, dry mouth, vomiting, toothache, gastroenteritis[Ref]


Common (1% to 10%): Urinary tract infection[Ref]


Common (1% to 10%): Seasonal allergy[Ref]


Common (1% to 10%): Decreased appetite[Ref]


Very common (10% or more): Back pain (up to 11.7%)

Common (1% to 10%): Musculoskeletal pain, muscle spasms[Ref]


Non-diabetic patients experienced events of blurred vision, dry eye, and visual impairment. Diabetic patients experienced visual disorders, conjunctival infections, irritations and inflammations, ocular sensation disorders, and cataract conditions.[Ref]

Common (1% to 10%): Eye disorder[Ref]


Frequency not reported: Increased incidence of cancer[Ref]

The U.S. Food and Drug Administration (FDA) reports that safety data from a lorcaserin clinical trial shows a possible increased risk of cancer. In this trial of 12,000 participants over 5 years, more patients taking lorcaserin were diagnosed with cancer compared to patients taking placebo. The cause of the cancer is uncertain, and it is unknown if this drug contributed to the cancer risk. The FDA will continue to evaluate the clinical trial results and communicate final conclusions and recommendations once the review is complete.[Ref]

More about Belviq XR (lorcaserin)

Patient resources

Other brands


Professional resources

Related treatment guides


1. "Product Information. Belviq (lorcaserin)." Eisai Inc (2012):

2. US Food and Drug Administration "Safety clinical trial shows possible increased risk of cancer with weightloss medicine Belviq, Belviq XR (lorcaserin)" (2020):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.