What You Need to Know About Casodex Side Effects

If you've been prescribed Casodex (Bicalutamide) for prostate cancer, it's normal to wonder about side effects. Every medication has them, and being informed helps you know what's expected, what's manageable, and what requires immediate medical attention.

Casodex is a nonsteroidal antiandrogen that works by blocking testosterone from reaching prostate cancer cells. Because it affects hormone levels throughout your body — not just in the prostate — side effects can show up in several areas. Most are manageable, but a few are serious and require monitoring.

What Is Casodex? (Quick Overview)

Casodex (Bicalutamide 50 mg) is an oral antiandrogen medication manufactured by AstraZeneca. It's FDA-approved to treat metastatic prostate cancer in combination with an LHRH analog such as Leuprolide (Lupron) or Goserelin (Zoladex). It's taken as one 50 mg tablet once daily. For a full overview, see our guide on what Casodex is and how it's used.

Common Side Effects of Casodex

The following side effects are commonly reported in clinical trials of Casodex used in combination with an LHRH analog. Many of these are related to the overall hormone suppression from the combined treatment, not just Casodex alone:

• Hot flashes — reported in approximately 53% of patients. This is the most common side effect and is caused by androgen suppression.
• General pain — affects about 35% of patients
• Back pain — reported in about 25% of patients
• Weakness (asthenia) — affects approximately 22% of patients
• Constipation — occurs in about 22% of patients
• Pelvic pain — reported in approximately 21% of patients
• Infection — affects about 18% of patients
• Nausea — occurs in approximately 15% of patients
• Peripheral edema (swelling) — affects about 13% of patients
• Shortness of breath (dyspnea) — reported in approximately 13% of patients
• Diarrhea — occurs in about 12% of patients
• Blood in urine (hematuria) — reported in approximately 12% of patients
• Gynecomastia (breast enlargement) — can occur due to androgen blockade
• Breast pain/tenderness — often accompanies gynecomastia

Most of these side effects are mild to moderate and tend to stabilize after the first few weeks of treatment. Hot flashes, while common, often become less frequent or intense over time.

Serious Side Effects

While uncommon, the following serious side effects require immediate medical attention:

Hepatotoxicity (Liver Injury)

This is the most important serious risk associated with Casodex. Rare cases of severe liver injury — including hospitalization and death — have been reported in patients taking Bicalutamide. Symptoms of liver problems include:

• Yellowing of the skin or eyes (jaundice)
• Dark-colored urine
• Persistent nausea or vomiting
• Upper right abdominal pain
• Unusual fatigue or weakness
• Loss of appetite

What your doctor should do: Liver function tests (LFTs) should be checked before starting Casodex and monitored regularly during treatment. If your liver enzymes become significantly elevated, your doctor may need to stop the medication.

Increased Bleeding Risk With Blood Thinners

Casodex can increase the effects of warfarin and other coumarin anticoagulants, raising your PT/INR and increasing the risk of serious bleeding. If you take a blood thinner, your doctor needs to monitor your clotting levels closely. Read more in our drug interactions guide.

Interstitial Lung Disease

Rarely, Bicalutamide has been associated with interstitial lung disease and pulmonary fibrosis. Symptoms include:

• New or worsening shortness of breath
• Dry, persistent cough
• Difficulty breathing with exertion

If you develop unexplained breathing problems while on Casodex, contact your doctor immediately.

Photosensitivity

Some patients experience increased sensitivity to sunlight while taking Bicalutamide. Use sunscreen (SPF 30+), wear protective clothing, and avoid prolonged sun exposure.

Diabetes and Cardiovascular Events

Androgen deprivation therapy (which includes Casodex plus an LHRH analog) has been associated with an increased risk of diabetes mellitus and cardiovascular events. Your doctor should monitor your blood sugar levels and cardiovascular health during treatment.

Side Effects in Specific Populations

Older Adults

Most patients taking Casodex for prostate cancer are older men. The side effects listed above are based on this population. Older patients may be more susceptible to fatigue, weakness, and falls — especially when combined with other medications.

Women (Off-Label Use)

Bicalutamide is sometimes prescribed off-label for conditions like hirsutism or as part of feminizing hormone therapy. In women, common side effects include dry skin, menstrual irregularities, and — importantly — the risk of liver toxicity still applies. Bicalutamide should absolutely never be used during pregnancy as it can cause serious harm to an unborn baby.

Patients With Liver Problems

Patients with moderate-to-severe hepatic impairment should use Casodex with caution. Bicalutamide is metabolized by the liver, and impaired liver function can increase drug exposure and toxicity risk.

How to Manage Common Side Effects

Here are practical tips for dealing with the most common Casodex side effects:

Hot Flashes

• Wear layers so you can adjust quickly
• Keep your bedroom cool at night
• Avoid spicy foods, caffeine, and alcohol, which can trigger hot flashes
• Talk to your doctor about medications that can help (some antidepressants like Venlafaxine have been shown to reduce hot flash frequency)

Nausea

• Take Casodex with food if nausea is an issue
• Eat smaller, more frequent meals throughout the day
• Avoid greasy or heavy foods
• Stay hydrated

Constipation

• Increase fiber intake (fruits, vegetables, whole grains)
• Drink plenty of water
• Stay physically active as tolerated
• Ask your doctor about a stool softener if dietary changes aren't enough

Weakness and Fatigue

• Light exercise — even a short daily walk — can actually improve energy levels
• Prioritize sleep and rest
• Don't push through extreme fatigue; pace your activities
• Talk to your doctor if fatigue is significantly affecting your daily life

Gynecomastia and Breast Pain

• This side effect is related to antiandrogen therapy and is generally not dangerous
• Talk to your doctor — in some cases, low-dose radiation therapy to the breast area before starting treatment can prevent or reduce gynecomastia
• Tamoxifen has been used off-label to manage this side effect in some patients

When to Call Your Doctor

Call your doctor right away if you experience any of the following:

• Signs of liver problems: Jaundice, dark urine, persistent nausea, upper right abdominal pain, unexplained fatigue
• Signs of bleeding: Unusual bruising, blood in stool or urine, prolonged bleeding from cuts
• Breathing problems: New or worsening shortness of breath, persistent dry cough
• Severe allergic reaction: Rash, hives, swelling of face/lips/tongue, difficulty breathing
• Chest pain or cardiovascular symptoms: Chest tightness, irregular heartbeat, sudden dizziness

Don't wait to see if these symptoms improve on their own. Early detection of serious side effects — especially liver injury — makes a significant difference in outcomes.

Final Thoughts

Most patients tolerate Casodex (Bicalutamide) well, especially given that it's a once-daily oral medication. The most common side effects — hot flashes, fatigue, and general pain — are manageable and often improve over time. The key is knowing what to watch for and staying on top of your regular lab monitoring.

Don't stop taking Casodex without talking to your doctor, even if side effects are bothersome. Your treatment team can often adjust your care plan to make side effects more manageable while keeping your cancer treatment on track.

Looking for more information? Read our guides on what Casodex is, drug interactions to watch for, and how to save money on your prescription. Need help finding a pharmacy with Casodex in stock? Visit Medfinder.