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).