Belviq Side Effects

Generic Name: lorcaserin

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

Not all side effects for Belviq may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

For the Consumer

Applies to lorcaserin: oral tablet

Along with its needed effects, lorcaserin (the active ingredient contained in Belviq) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking lorcaserin:

More common
  • Anxiety
  • bladder pain
  • bloody or cloudy urine
  • blurred vision
  • body aches or pain
  • chills
  • cold sweats
  • coma
  • confusion
  • cool, pale skin
  • cough
  • depression
  • difficult, burning, or painful urination
  • difficulty with breathing
  • dizziness
  • ear congestion
  • fast heartbeat
  • fever
  • frequent urge to urinate
  • headache
  • increased hunger
  • loss of voice
  • lower back or side pain
  • nasal congestion
  • nausea
  • nightmares
  • pounding in the ears
  • runny nose
  • seizures
  • shakiness
  • slow or fast heartbeat
  • slurred speech
  • sneezing
  • sore throat
  • swelling of the breasts or breast soreness in both females and males
  • unexpected or excess milk flow from the breasts
  • unusual tiredness or weakness
Less common
  • Bloating or swelling of the face, arms, hands, lower legs, or feet
  • decreased ability to exercise
  • dry mouth
  • flushed, dry skin
  • fruit-like breath odor
  • increased hunger
  • increased sensitivity to sunlight
  • increased thirst
  • increased urination
  • itching, pain, redness, or swelling of the eye or eyelid
  • joint pain
  • loss of consciousness
  • rapid weight gain
  • severe skin rash or hives
  • stomachache
  • sweating
  • swollen glands
  • tingling of the hands or feet
  • trouble with breathing
  • trouble with sleeping
  • unexplained weight loss
  • unusual weight gain or loss
  • vomiting
  • watering of the eyes
  • Black, tarry, stools
  • chest pain
  • cough or hoarseness
  • pale skin
  • sores, ulcers, or white spots on the lips or in the mouth
  • swollen glands
  • unusual bleeding or bruising
Incidence not known
  • Agitation
  • confusion
  • convulsions
  • diarrhea
  • high fever
  • increased sweating
  • loss of bladder control
  • overactive reflexes
  • painful or prolonged erection of the penis
  • poor coordination
  • restlessness
  • severe muscle stiffness
  • shivering
  • talking or acting with excitement you cannot control
  • trembling or shaking
  • twitching
  • unusually pale skin

Get emergency help immediately if any of the following symptoms of overdose occur while taking lorcaserin:

Symptoms of overdose
  • Abdominal or stomach discomfort
  • false or unusual sense of well-being
  • seeing, hearing, or feeling things that are not there

Some side effects of lorcaserin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
  • Back pain
  • difficulty having a bowel movement (stool)
  • muscle aches
Less common
  • Decreased appetite
  • difficulty with concentration
  • dry eyes
  • muscle spasms
  • muscle, joint, or bone pain
  • problems with memory
  • rash
  • sleeplessness
  • stress
  • toothache
  • trouble seeing

For Healthcare Professionals

Applies to lorcaserin: oral tablet


Cardiovascular side effects have included hypertension (up to 5.1%) and peripheral edema (up to 4.7%).


Gastrointestinal side effects have included nausea (up to 9.4%), diarrhea (up to 6.5%), constipation (up to 5.8%), dry mouth (up to 5.3%), vomiting (up to 3.8%), toothache (up to 2.7%), gastroenteritis (3.1%), and decreased appetite (up to 2.3%).


Genitourinary side effects have included urinary tract infection (up to 9%).


Hematologic side effects have included decreases in white blood cell count (including leukopenia, lymphopenia, neutropenia, and decreased white cell count) (0.4%), and decreases in red blood cell count (including anemia and decreases in hemoglobin and hematocrit) (1.3%).


Hypersensitivity side effects have included seasonal allergy (up to 3.1%).


Immunologic side effects have included moderately elevated prolactin levels. Prolactin should be measured when symptoms and signs of prolactin excess are suspected (e.g., galactorrhea, gynecomastia).


Local side effects have included rash (up to 2.1%).


Metabolic side effects in patients with diabetes mellitus have included hypoglycemia (up to 29.3%) and worsening of diabetes mellitus (up to 2.7%).


Musculoskeletal side effects have included back pain (up to 11.7%), musculoskeletal pain (up to 2%), and muscle spasms (up to 4.7%).

Nervous system

Nervous system side effects have included fatigue (up to 7.4%), headache (up to 16.8%), and dizziness (up to 7%).


Ocular side effects have included blurred vision, dry eye, and visual impairment (up to 4.5%) in patients without diabetes. Type 2 diabetic patients (up to 6.3%) experienced visual disorders, conjunctival infections, irritations, and inflammations, ocular sensation disorders, and cataract conditions.


Psychiatric side effects have included anxiety (up to 3.5%), insomnia (up to 3.5%), stress (up to 2.7%), depression (up to 2.3%), and cognitive impairment (e.g., difficulty with concentration/attention, difficulty with memory, and confusion) (up to 2.3%).


Respiratory side effects have included upper respiratory tract infection (up to 13.7%), nasopharyngitis (up to 13%), cough (up to 8.2%) oropharyngeal pain (up to 3.5%), and sinus congestion (up to 2.9%).

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