Tranexamic Acid Side Effects: What to Expect and When to Call Your Doctor

Tranexamic acid is generally considered safe and well-tolerated — particularly at the oral doses used for heavy menstrual bleeding. But like any medication, it carries both common mild side effects and rare but serious risks that every patient should be aware of. Here's a clear breakdown of what to expect, what to watch for, and when to seek medical attention.

Common Side Effects of Tranexamic Acid

Most patients who take oral tranexamic acid for heavy menstrual bleeding experience few or no side effects. When side effects do occur, they are typically mild and tend to improve as your body adjusts. The most commonly reported side effects include:

Nausea: The most frequently reported side effect. Taking tranexamic acid with food may reduce nausea. If it's severe, call your doctor.

Headache: Reported by some patients, usually mild. A severe or sudden-onset headache is a warning sign that warrants immediate medical attention (see serious side effects below).

Back pain: Reported in clinical trials, usually mild to moderate.

Abdominal pain or stomach discomfort: May occur with oral tablets; taking with food can help.

Diarrhea or vomiting: Less common but reported with both oral and IV formulations.

Dizziness: Patients are advised not to drive if they experience dizziness. More common with IV formulations.

Allergic dermatitis: Skin rash or irritation. Notify your doctor if you develop a rash.

Serious Side Effects: Call Your Doctor Immediately

Although rare, tranexamic acid can cause serious adverse events. Seek emergency medical care (call 911 or go to the ER) if you experience any of the following:

Blood Clots (Thromboembolism)

Tranexamic acid can increase the risk of blood clots by preventing clots from breaking down. Signs of a blood clot include:

Pain, redness, swelling, or warmth in one leg (possible DVT — deep vein thrombosis)

Sudden chest pain, shortness of breath, or rapid heartbeat (possible pulmonary embolism)

Numbness or weakness on one side of the body, sudden vision changes, or difficulty speaking (possible stroke)

Coughing up blood

Tranexamic acid is contraindicated for patients with a history of or active blood clots (DVT, PE, stroke). If you have a history of clotting problems, tell your doctor before starting this medication.

Seizures

Seizures have been reported with tranexamic acid, primarily with intravenous use — especially when accidentally given into the neuraxial space (spine). Seizures can also occur at very high IV doses used in cardiac surgery. The 2025 FDA labeling updates strengthened warnings about this risk. For oral formulations at standard HMB doses, seizure risk is extremely low.

Visual Disturbances

Retinal toxicity has been observed in animal studies at high doses. Patients on long-term oral tranexamic acid therapy (particularly those treated for conditions other than HMB) should have periodic eye exams including visual acuity and color vision testing. If you experience sudden changes in vision, blurred vision, or color vision changes, stop the medication and contact your doctor.

Severe Allergic Reactions (Anaphylaxis)

Though rare, severe hypersensitivity reactions including anaphylaxis have been reported. Signs include hives, swelling of the face or throat, difficulty breathing, and severe dizziness. This is a medical emergency — call 911 immediately.

Who Should NOT Take Tranexamic Acid?

Tranexamic acid oral tablets are contraindicated in:

Patients with a history of or active thromboembolic disease (DVT, PE, stroke, heart attack)

Patients with an intrinsic risk of thromboembolic events (e.g., thrombogenic valve disease, certain heart rhythm disorders, inherited clotting disorders)

Patients with known allergy to tranexamic acid

Patients who are taking hormonal contraceptives with estrogen (combination pill) — increased clot risk

Side Effects vs. Expected Effects

When it's working correctly, tranexamic acid reduces the amount of menstrual blood you lose. Some women notice their periods become lighter, shorter, or both. This is an expected therapeutic effect — not a sign that something is wrong. If your periods don't become lighter after 2-3 cycles, talk to your doctor about whether the medication is working for you.

The Bottom Line

For most patients taking tranexamic acid orally for heavy menstrual bleeding, side effects are mild and manageable. The serious risks — blood clots, seizures, severe allergic reactions — are rare but real. Know the warning signs and don't hesitate to seek emergency care if they appear. For information on what drugs and supplements interact with tranexamic acid, see our guide on tranexamic acid drug interactions.