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 Arimidex (Anastrozole). If you are concerned about side effects, discuss the risks and benefits of Arimidex (Anastrozole) with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. 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
• Diarrhea
• dizziness
• hair thinning
• headache
• hot flashes
• increased or decreased appetite
• muscle stiffness
• nausea or vomiting
• pain in muscles, bones, or joints
• skin rash
• taste changes
• trouble sleeping
• vaginal dryness
• weakness
• weight gain

Although most of the 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:

• abdominal pain
• bone fractures
• increased blood pressure
• increased cholesterol levels
• signs of Carpal Tunnel Syndrome (e.g. tingling pain, coldness, and weakness in parts of the hand)
• signs of infection (e.g., severe Fever, chills, mouth ulcers, shortness of breath, sudden lack of energy)
• signs of Depression (such as feeling sad, losing interest in things you used to enjoy, weight changes, changes in sleep habits, feelings of guilt or worthlessness, thoughts of suicide)
• swelling of the feet, legs, or arms
• unusual vaginal discharge, itching, or bleeding
• vision changes

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

• signs of a blood clot in the arm or leg (tenderness, pain, swelling, warmth, or redness in the arm or leg) or lungs (difficulty breathing, sharp chest pain that is worst when breathing in, coughing, coughing up blood, sweating, or passing out)
• signs of a Heart Attack (e.g., tightness or feeling of heaviness in your chest or pain radiating to your arms or shoulders, neck, teeth, jaw, abdomen or back)
• symptoms of liver problems (e.g., abdominal pain, persistent vomiting, feeling unwell, fever, itching, yellowing of the skin and eyes, dark urine)
• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
• 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 Arimidex (Anastrozole).

Each white, biconvex, film-coated tablet intagliated with "Adx 1" on one side and a logo on the other ("A" for ARIMIDEX) contains 1 mg of Arimidex (Anastrozole). Nonmedicinal ingredients: hypromellose, lactose monohydrate, macrogol 300, magnesium stearate, povidone, sodium starch glycolate, and titanium dioxide.

Do not use Arimidex (Anastrozole) if you:

• are allergic to Arimidex (Anastrozole) or any ingredients of the medication
• are allergic to any other aromatase inhibitor medications (e.g., Letrozole, Exemestane)
• are breast-feeding
• are pregnant

There may be an interaction between Arimidex (Anastrozole) and any of the following:

• any estrogen-containing medications
• Aripiprazole
• dofetilide
• Hydrocodone
• Lomitapide
• Methadone
• Pimozide
• Tamoxifen
• 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 Arimidex (Anastrozole). 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 this medication.

There are certain circumstances and medical conditions where this medication is not recommended, or should be taken with caution. Be sure to inform your physician of all your medical conditions before you begin therapy.

Bone mineral density: Long-term use of Arimidex (Anastrozole) may decrease the density of bones, thereby increasing the risk of Osteoporosis. Your doctor will order bone mineral density tests periodically while you are taking Arimidex (Anastrozole).

Drowsiness/dizziness: Arimidex (Anastrozole) may cause dizziness or drowsiness. If you experience either or both of these side effects, you should not drive, use machinery, or perform any other activities that require alertness.

Heart disease: Arimidex (Anastrozole) may increase the risk of heart attack or increased blood pressure. If you are at risk for heart disease or high blood pressure, discuss with your doctor how Arimidex (Anastrozole) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Arimidex (Anastrozole), and whether any special monitoring is needed. If you experience signs of a heart attack, such as tightness or heaviness in your chest, sudden chest pain spreading to your arms or shoulders, sweating, nausea, or anxiety, seek medical help immediately.

Kidney function: If you have reduced kidney function, discuss with your doctor how Arimidex (Anastrozole) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Arimidex (Anastrozole), and whether any special monitoring is needed.

Liver function: If you have liver disease or reduced liver function, discuss with your doctor how Arimidex (Anastrozole) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Arimidex (Anastrozole), and whether any special monitoring is needed.

Pre-menopausal women: You should not use Arimidex (Anastrozole) if you have not yet started Menopause.

Pregnancy: Although Arimidex (Anastrozole) has not been studied with pregnant women (it is intended for use only by women who have passed menopause), it is suspected that it could cause serious problems, possibly including miscarriage. Therefore, it should not be used during pregnancy. Tell your doctor immediately if you become pregnant.

Breast-feeding: It is not known whether Arimidex (Anastrozole) passes into breast milk. Because of the risks associated with this drug, women using this medication should not breast-feed.