What You Should Know About Aminocaproic Acid Side Effects

Every medication comes with potential side effects, and Aminocaproic Acid (brand name Amicar) is no exception. Whether you've just started this medication or you're considering it, knowing what to watch for can help you feel more prepared — and know when something needs medical attention.

This guide covers the most common side effects, the serious ones to watch for, and practical tips for managing them. All of this information comes from FDA labeling and clinical data.

What Is Aminocaproic Acid?

Aminocaproic Acid is an antifibrinolytic medication that helps prevent excessive bleeding by stabilizing blood clots. It's used for bleeding syndromes caused by elevated fibrinolytic activity, including bleeding during cardiac surgery, bleeding disorders, and other conditions. For a deeper look at what this drug does and how it works, check out our articles on what Aminocaproic Acid is and how it works.

Common Side Effects

These side effects are relatively frequent and are usually mild. They often improve as your body adjusts to the medication:

• Nausea — One of the most commonly reported side effects. Taking the medication with food may help.
• Vomiting
• Diarrhea
• Stomach pain or abdominal discomfort
• Headache
• Dizziness
• Muscle pain or weakness — This is especially important to monitor (see serious side effects below).
• Stuffy nose
• Watery eyes
• Fatigue
• Skin rash
• Decreased ejaculate volume — This typically reverses when the medication is stopped.

Most of these side effects are manageable and don't require you to stop taking the medication. However, if any of them become severe or don't go away, let your doctor know.

Serious Side Effects — When to Call Your Doctor

Some side effects of Aminocaproic Acid can be dangerous and require immediate medical attention. Call your doctor right away — or go to the emergency room — if you experience any of the following:

Blood Clots (Thrombosis)

Because Aminocaproic Acid works by preventing clot breakdown, there is a risk that it can promote excessive clotting. Watch for:

• Swelling, pain, or warmth in one leg (possible deep vein thrombosis/DVT)
• Sudden shortness of breath or chest pain (possible pulmonary embolism/PE)
• Sudden weakness or numbness on one side of the body (possible stroke)

The risk of thrombosis is higher if you are also taking hormonal contraceptives, Factor IX concentrates, or other clotting agents.

Rhabdomyolysis and Muscle Damage

Aminocaproic Acid can cause skeletal muscle damage ranging from mild myopathy to severe rhabdomyolysis. This is one of the most important side effects to watch for. Symptoms include:

• Severe or worsening muscle pain, tenderness, or weakness
• Dark brown or cola-colored urine
• Unexplained fatigue

If you notice progressive muscle weakness or darkened urine, stop taking the medication and contact your doctor immediately. Rhabdomyolysis can lead to kidney failure if untreated.

Kidney Problems

Aminocaproic Acid is cleared through the kidneys, and it can cause acute renal failure. It may also cause intrarenal obstruction, especially in patients with upper urinary tract bleeding. Symptoms to watch for:

• Significant decrease in urination
• Swelling in the legs or ankles
• Extreme fatigue or confusion

Other Serious Side Effects

• Seizures
• Bradycardia (unusually slow heart rate) — you may feel faint or lightheaded
• Hypotension (low blood pressure) — dizziness upon standing, fainting
• Allergic reactions — hives, swelling of the face/throat, difficulty breathing. Seek emergency care immediately.

Side Effects in Specific Populations

Kidney Disease

If you have impaired kidney function, Aminocaproic Acid is cleared more slowly from your body. This means side effects may be more intense or last longer. Your doctor may adjust your dose or monitor you more closely with blood tests.

Pregnancy

Aminocaproic Acid is classified as Pregnancy Category C. This means animal studies have shown potential risks, but there aren't enough studies in pregnant humans. It should only be used during pregnancy if the potential benefit justifies the potential risk. If you are pregnant or planning to become pregnant, discuss this with your doctor.

Breastfeeding

It is not known whether Aminocaproic Acid passes into breast milk. If you are breastfeeding, talk to your doctor about the risks and benefits before starting this medication.

Adolescents

Weight-based dosing is recommended for adolescents. Your doctor will calculate the appropriate dose based on body weight.

How to Manage Side Effects

Here are some practical tips to help manage the more common side effects:

• Nausea and stomach pain: Take Aminocaproic Acid with food or a light snack. Sipping water throughout the day can also help.
• Dizziness: Stand up slowly from sitting or lying positions. Avoid driving or operating heavy machinery until you know how the medication affects you.
• Muscle pain: Report any muscle pain to your doctor right away, even if it seems mild. Your doctor may order a creatine kinase (CK) blood test to check for muscle damage. Do not assume muscle aches are "normal."
• Headache: Over-the-counter pain relievers may help, but ask your doctor before taking anything new — especially NSAIDs, which can affect bleeding.
• Fatigue: Rest when needed. This side effect often improves after the first few days of treatment.

Never stop taking Aminocaproic Acid without talking to your doctor first. Stopping suddenly during treatment for active bleeding can cause your bleeding to return or worsen.

Final Thoughts

Most people tolerate Aminocaproic Acid without serious problems, especially when it's used for a short period under medical supervision. The most important things to watch for are signs of blood clots, muscle damage, and kidney problems.

If you're taking Aminocaproic Acid and experience any concerning symptoms, don't wait — contact your healthcare provider. And if you're having trouble finding this medication at your pharmacy, Medfinder can help you locate a pharmacy with Aminocaproic Acid in stock.