SIDE EFFECTS: Side effects with carbidopa are rare and usually occur due to the effect of levodopa or other drugs used along with this medication. Consult the Side Effects information of the levodopa-containing product(s) as well as any other drugs you are using. If you have any questions or notice any effects, consult your doctor or pharmacist.

Tell your doctor immediately if you notice worsening involuntary muscle movements/spasms, greatly increased eye blinking/twitching, or mental/mood changes (e.g., confusion, depression, hallucinations, thoughts of suicide). Your doctor may decide to lower your levodopa dose.

Dizziness, nausea, and vomiting may occur. If any of these effects persist or worsen, contact your doctor or pharmacist promptly.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor immediately if any of these unlikely but serious side effects occur: irregular heartbeat, fainting.

Tell your doctor immediately if any of these rare but very serious side effects occur: easy bleeding/bruising, signs of infection (e.g., fever, persistent sore throat), tingling of the hands/feet, vision changes (e.g., blurred/double vision).

Seek immediate medical attention if any of these rare but very serious side effects occur: chest pain, seizures, vomit that looks like coffee grounds, black/tarry stools.

Abruptly stopping or reducing the dose of this medication may rarely cause a serious (sometimes fatal) condition (neuroleptic malignant syndrome). Seek immediate medical attention if any of these rare but very serious side effects occur: fast/shallow breathing, confusion, severe dizziness/fainting, high fever, muscle stiffness, unusual sweating.

For males, in the very unlikely event you have a painful or prolonged erection (lasting more than 4 hours), stop using this drug and seek immediate medical attention or permanent problems could occur.

A very serious allergic reaction is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction include: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Read the Lodosyn (carbidopa) Side Effects Center for a complete guide to possible side effects »

PRECAUTIONS: Before taking this medication, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: certain eye problem (narrow-angle glaucoma).

Before using this medication, tell your doctor or pharmacist your medical history, especially of: breathing problems (e.g., asthma, emphysema), certain eye problem (wide-angle glaucoma), heart or blood vessel problems (e.g., arrhythmias, heart attack, angina), kidney disease, liver disease, mental/mood disorders (e.g., depression, schizophrenia), peptic ulcer, seizure.

This drug may make you dizzy or cause blurred vision. Do not drive, use machinery, or do any activity that requires alertness or clear vision until you are sure you can perform such activities safely. Avoid alcoholic beverages.

To minimize lightheadedness, get up slowly when rising from a sitting or lying position.

Before having surgery, tell your doctor or dentist that you are taking this medication.

This medication should be used only when clearly needed during pregnancy. Discuss the risks and benefits with your doctor.

It is unknown if this medication passes into breast milk. Consult your doctor before breast-feeding.