Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes Gemzar (Gemcitabine). If you are concerned about side effects, discuss the risks and benefits of Gemzar (Gemcitabine) with your doctor.

The following side effects have been reported by at least 1% of people taking Gemzar (Gemcitabine). Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• Constipation (mild)
• Diarrhea
• fatigue
• flu-like symptoms (most commonly after the first dose of Gemzar (Gemcitabine)) including:
• chills
• cough
• difficulty sleeping
• feeling of illness
• Fever (not associated with infection)
• headache
• muscle pain
• runny nose
• sweating
• weakness
• nausea and vomiting (for less than 24 hours)
• numbness or tingling of hands or feet
• temporary hair loss (minimal)

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• fast or irregular heartbeat
• high blood pressure
• pain at site of injection
• severe constipation for 3 days that has not been relieved by laxatives
• severe diarrhea (3 or more watery bowel movements per day lasting more than 24 hours)
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood,  bleeding gums, cuts that don't stop bleeding)
• signs of kidney problems (e.g., increased urination at night, decreased urine production, blood in the urine, change of urine colour)
• signs of  liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• skin rash
• sores on mouth or lips
• swelling of fingers, feet, or lower legs
• symptoms of Anemia (i.e., shortness of breath, paleness, tiredness, fast heart rate, yellowing of the skin or eyes, dark urine)
• symptoms of infection (i.e., fever, cough, chills, difficult or painful urination, pain in the side or lower back)
• vision changes
• vomiting lasting more than 24 hours after treatment

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of bleeding in the stomach (e.g., bloody, black, or  tarry stools, spitting up of blood, vomiting blood or material that looks like coffee grounds)
• signs of breathing problems (e.g., shortness of breath, troubled breathing, wheezing, or tightness in chest, fast or irregular breathing)
• signs of posterior reversible encephalopathy syndrome (e.g., headache, seizures, weakness, confusion, high blood pressure, vision changes, difficulty thinking clearly)
• signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking Gemzar (Gemcitabine).

Gemzar (Gemcitabine) should not be used by anyone who is allergic to Gemzar (Gemcitabine) or to any of the ingredients of the medication.

There may be an interaction between Gemzar (Gemcitabine) and any of the following:

• acetylsalicylic acid (Asa)
• amphotericin B
• Bleomycin
• other cancer medications
• Clozapine
• Deferiprone
• Denosumab
• Digoxin
• dipyrone
• echinacea
• Fingolimod
• Fluorouracil
• Leflunomide
• Natalizumab
• Nivolumab
• Pimecrolimus
• Roflumilast
• Tacrolimus
• Tofacitinib
• Trastuzumab
• vaccines
• Warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Gemzar (Gemcitabine). Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use Gemzar (Gemcitabine).

Blood clotting: Gemzar (Gemcitabine) can reduce the number of platelet cells in the blood. Your doctor will monitor the number of platelets in your blood with regular blood tests while you are using Gemzar (Gemcitabine). Platelets help the blood to clot, and a shortage could make you bleed more easily. Tell your doctor of any signs that your blood is not clotting as quickly. Such symptoms may include black and tarry stools, nosebleeds, bleeding gums, blood in the urine, easy bruising, or cuts that won't stop bleeding.

Fever and flu-like symptoms: Gemzar (Gemcitabine) can cause a fever and flu-like symptoms (chills, feeling unwell) that are not associated with an infection. Your doctor may prescribe Acetaminophen to help treat this reaction.

Infection: As well as killing cancer cells, Gemzar (Gemcitabine) can reduce the number of cells that fight infection in the body (white blood cells). Avoid contact with people who have contagious infections and tell your doctor if you begin to notice signs of an infection, such as fever or chills. Your doctor will monitor the number of white blood cells in your blood with regular blood tests while you are using Gemzar (Gemcitabine).

Kidney problems: Rarely, Gemzar (Gemcitabine) can cause a rapid breakdown of red blood cells that can be associated with kidney failure and may be fatal. Your doctor will monitor you for this while you are receiving Gemzar (Gemcitabine). People who have kidney problems should discuss with their doctor how Gemzar (Gemcitabine) may affect their medical condition, how their medical condition may affect the dosing and effectiveness of Gemzar (Gemcitabine), and whether any special monitoring is needed.

Liver problems: Gemzar (Gemcitabine) may reduce liver function and can cause liver failure. If you have liver problems, discuss with your doctor how Gemzar (Gemcitabine) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Gemzar (Gemcitabine), and whether any special monitoring is needed.

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Lung inflammation: Lung inflammation, causing difficulty breathing has occurred rarely in some people taking Gemzar (Gemcitabine). This complication can be serious and sometimes fatal. If you experience new or worsening shortness of breath or cough (with or without fever) at any time while you are taking Gemzar (Gemcitabine) contact your doctor immediately.

Reversible Posterior Leukoencephalopathy Syndrome (RPLS): This is a rare disease of the brain that may occur when using medications like Gemzar (Gemcitabine). If you have had a previous episode of RPLS, Gemzar (Gemcitabine) may not be an appropriate medication for you. If you experience signs and symptoms of RPLS, such as headache, seizures, change in awareness or consciousness or vision changes, contact your doctor immediately.

Pregnancy: Gemzar (Gemcitabine) should not be used during pregnancy. Effective birth control should be used while receiving Gemzar (Gemcitabine). Gemzar (Gemcitabine) may harm the baby if used during pregnancy. If you become pregnant while taking Gemzar (Gemcitabine), contact your doctor immediately.

Breast-feeding: It is not known if Gemzar (Gemcitabine) passes into breast milk. Women receiving Gemzar (Gemcitabine) should not breast-feed.

Children: The safety and effectiveness of using Gemzar (Gemcitabine) have not been established for children.