Belviq affects chemical signals in the brain that control appetite. Lorcaserin works by helping you feel full with smaller meals.

Belviq is used together with diet and exercise to treat obesity.

Belviq is sometimes used to treat obesity that may be related to diabetes, high cholesterol, or high blood pressure.

Belviq will not treat any underlying health condition (such as heart disease, diabetes, high blood pressure). Keep taking any other medications your doctor has prescribed to treat these conditions.

Do not use Belviq if you are pregnant. Weight loss during pregnancy can harm an unborn baby, even if you are overweight.

Serious drug interactions can occur when certain medicines are used together with lorcaserin. Tell each of your healthcare providers about all medicines you use now, and any medicine you start or stop using.

Before you take Belviq, tell your doctor if you have diabetes, congestive heart failure, a heart valve disorder, sickle cell anemia, leukemia or myeloma, kidney or liver disease, or a physical deformity of the penis (such as Peyronie's disease).

Belviq may be habit-forming and should be used only by the person for whom it was prescribed. Keep the medication in a secure place where others cannot get to it.

Tell your doctor if you do not lose at least 5% of your starting weight after taking the medication for 12 weeks.

Belviq is only part of a complete program of treatment that also includes diet, exercise, weight control, and possibly testing your blood sugar.

Take Belviq exactly as prescribed by your doctor. Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

The regular tablet is usually taken 2 times per day. The extended-release tablet is taken only once per day. Follow your doctor's instructions.

Swallow the extended-release tablet whole and do not crush, chew, or break it.

You may take Belviq with or without food.

You should lose at least 5% of your starting weight during the first 12 weeks of taking Belviq and eating a low calorie diet. Call your doctor if you do not lose at least 5% of your starting weight after taking the medicine for 12 weeks.

Belviq is only part of a complete program of treatment that also includes diet, exercise, weight control, and possibly testing your blood sugar. Follow your diet, medication, and exercise routines very closely.

Do not share Belviq with another person. Keep the medication in a place where others cannot get to it.

Store at room temperature away from moisture and heat. Keep track of your medicine. You should be aware if anyone is using it improperly or without a prescription.

You should not use Belviq if you are allergic to lorcaserin.

Do not use lorcaserin if you are pregnant. Weight loss during pregnancy can harm an unborn baby, even if you are overweight. Tell your doctor right away if you become pregnant during treatment.

To make sure lorcaserin is safe for you, tell your doctor if you have ever had:

• diabetes;

• congestive heart failure;

• a heart valve disorder;

• slow heartbeats or heart block (especially 2nd or 3rd degree "AV block");

• sickle cell anemia;

• leukemia or myeloma;

• kidney or liver disease; or

• a physical deformity of the penis (such as Peyronie's disease).

In clinical studies, more people taking Belviq were diagnosed with cancer compared with people taking an inactive placebo. It is not clear whether lorcaserin actually causes cancer. Talk to your doctor about your own cancer risk while taking Belviq.

You should not breastfeed while using lorcaserin.

Belviq is not approved for use by anyone younger than 18 years old.

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Avoid driving or hazardous activity until you know how lorcaserin will affect you. Your reactions could be impaired.

Avoid taking cough and cold or allergy medications while taking lorcaserin.

Do not take any other prescription or over-the-counter weight-loss products without your doctor's advice.

Get emergency medical help if you have signs of an allergic reaction to Belviq: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Stop using Belviq and call your doctor at once if you have:

• unusual changes in mood or behavior, thoughts of suicide or hurting yourself;

• dry eyes, blurred vision;

• feelings of standing next to yourself or being outside of your body;

• memory problems, trouble concentrating;

• breast swelling (in women or men), nipple discharge;

• penis erection that is painful or lasts longer than 4 hours;

• heart problems--fast heart rate, trouble breathing, dizziness, ongoing weakness, or swelling in your arms, hands, legs, or feet;

• high levels of serotonin in the body--agitation, hallucinations, fever, fast heart rate, overactive reflexes, nausea, vomiting, diarrhea, loss of coordination, fainting; or

• severe nervous system reaction--very stiff (rigid) muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors, feeling like you might pass out.

Common Belviq side effects may include:

• headache, dizziness, feeling tired;

• dry mouth, cough;

• nausea, constipation;

• back pain; or

• low blood sugar (in people with diabetes).

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Tell your doctor about all your current medicines and any you start or stop using, especially:

• cabergoline;

• linezolid;

• lithium;

• St. John's wort;

• tramadol;

• tryptophan (also called L-tryptophan);

• any type of antidepressant;

• cold or cough medicine that contains dextromethorphan (a cough suppressant);

• erectile dysfunction medicine--avanafil, sildenafil, tadalafil, Cialis, Levitra, Viagra, and others;

• medicine to treat mental illness, anxiety, or a mood disorder; or

• a "triptan" migraine headache medicine--such as almotriptan, frovatriptan, rizatriptan, sumatriptan, zolmitriptan, Imitrex, Maxalt, Zomig, and others.

This list is not complete. Other drugs may interact with lorcaserin, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.