Medically reviewed on June 7, 2018
Commonly used brand name(s)
In the U.S.
- Belviq XR
Available Dosage Forms:
- Tablet, Extended Release
Therapeutic Class: Antiobesity Agent
Uses For This Medicine
Lorcaserin is used together with a reduced-calorie diet and proper exercise to help you lose weight. It is also used in overweight people who may also have diabetes, high blood pressure, high cholesterol, or heart disease.
Lorcaserin is available only with your doctor's prescription.
Before Using This Medicine
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For lorcaserin, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to lorcaserin or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies have not been performed on the relationship of age to the effects of lorcaserin in the pediatric population. Safety and efficacy have not been established.
Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of lorcaserin in the elderly. However, elderly patients are more likely to have kidney problems, which may require caution and an adjustment in the dose for patients receiving lorcaserin.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with Medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking lorcaserin, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using lorcaserin with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
Using lorcaserin with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Methylene Blue
- Morphine Sulfate Liposome
- St John's Wort
Interactions with Food/Tobacco/Alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.
Other Medical Problems
The presence of other medical problems may affect the use of lorcaserin. Make sure you tell your doctor if you have any other medical problems, especially:
- Bradycardia (slow heartbeat) or
- Congestive heart failure or
- Depression or
- Diabetes or
- Heart block, history of or
- Heart valvular disease or
- Hyperprolactinemia (high prolactin in the blood) or
- Hypoglycemia (low blood sugar) or
- Mental illness, history of or
- Pulmonary hypertension, history of—Use with caution. May make these conditions worse.
- Kidney disease, moderate or
- Liver disease, severe—Use with caution. The effects may be increased because of slower removal of the medicine from the body.
- Kidney disease, severe or end-stage—Use is not recommended in patients with this condition.
- Abnormal penis, including curved penis, birth defects of the penis, and Peyronie's disease or
- Leukemia (blood related cancer) or
- Multiple myeloma (blood related cancer) or
- Sickle-cell anemia (blood disorder)—Lorcaserin should be used with caution in these patients as problems with prolonged erection of the penis may occur.
Proper Use of This Medicine
Take lorcaserin only as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.
Lorcaserin comes with a patient information insert. Read and follow the instructions carefully. Ask your doctor if you have any questions.
You may take lorcaserin with or without food.
Carefully follow your doctor's instructions for a reduced-calorie diet plan and regular exercise. Talk with your doctor before starting any exercise program.
Your doctor should tell you to stop taking lorcaserin if you do not lose a certain amount of weight within the first 12 weeks of treatment.
The dose of lorcaserin will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of lorcaserin. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For oral dosage form (tablets):
- For weight loss:
- Adults—10 milligrams (mg) two times a day.
- Children—Use is not recommended.
- For weight loss:
If you miss a dose of lorcaserin, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Precautions While Using This Medicine
It is very important that your doctor check your progress at regular visits, to make sure that lorcaserin is working properly. Blood tests may be needed to check for unwanted effects.
Using lorcaserin while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. If you think you have become pregnant while using lorcaserin, tell your doctor right away.
Make sure your doctor knows about all the other medicines you are using. Lorcaserin may cause serious conditions, such as serotonin syndrome or neuroleptic malignant syndrome (NMS)-like reactions, when taken with certain medicines. Call your doctor right away if you have a fever, confusion, mental changes, restlessness, fast heartbeat, muscle spasms, trouble walking, nausea, vomiting, or diarrhea.
Check with your doctor right away if you have rapid weight gain, swelling of the ankles, feet, or lower legs, or troubled breathing while using lorcaserin.
Lorcaserin may cause dizziness, drowsiness, trouble in thinking, or poor judgment. Make sure you know how you react to lorcaserin before you drive, use machines, or do other jobs that require you to be alert or able to think well.
If you develop any unusual and strange thoughts or behavior while you are taking lorcaserin, be sure to discuss it with your doctor. Some changes may be more unusual and extreme, such as confusion, worsening of depression, hallucinations (seeing, hearing, or feeling things that are not there), suicidal thoughts, and unusual excitement, nervousness, or irritability.
For patients with diabetes: Weight loss may result in an improvement in your condition, but may increase your chance of having hypoglycemia (low blood sugar). You should check your blood sugar more often before taking lorcaserin and during Belviq® treatment. If you notice any changes in your blood sugar levels, check with your doctor.
If you experience a prolonged or painful erection for 4 hours or more, contact your doctor immediately. This condition may require prompt medical treatment to prevent serious and permanent damage to your penis.
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal (e.g., St. John's wort) or vitamin supplements.
This Medicine Side Effects
Along with its needed effects, a medicine 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:
- bladder pain
- bloody or cloudy urine
- blurred vision
- body aches or pain
- cold sweats
- cool, pale skin
- difficult, burning, or painful urination
- difficulty with breathing
- ear congestion
- fast heartbeat
- frequent urge to urinate
- increased hunger
- loss of voice
- lower back or side pain
- nasal congestion
- pounding in the ears
- runny nose
- slow or fast heartbeat
- slurred speech
- 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
- 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
- swollen glands
- tingling of the hands or feet
- trouble with breathing
- trouble with sleeping
- unexplained weight loss
- unusual weight gain or loss
- 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
- high fever
- increased sweating
- loss of bladder control
- overactive reflexes
- painful or prolonged erection of the penis
- poor coordination
- severe muscle stiffness
- talking or acting with excitement you cannot control
- trembling or shaking
- unusually pale skin
Get emergency help immediately if any of the following symptoms of overdose occur:
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 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:
- Back pain
- difficulty having a bowel movement (stool)
- muscle aches
- Decreased appetite
- difficulty with concentration
- dry eyes
- muscle spasms
- muscle, joint, or bone pain
- problems with memory
- trouble seeing
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
See also: Side effects (in more detail)
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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More about lorcaserin
- Lorcaserin Side Effects
- During Pregnancy
- Dosage Information
- Drug Interactions
- Support Group
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