Do not use Prazosin if:

• you are allergic to any ingredient in Prazosin;
• you are taking modafinil.

• Prazosin may cause dizziness, lightheadedness, or fainting after the first dose. Take the first dose at bedtime. If you get up during the night, sit up and stand slowly. Continue to sit up and stand slowly while you are taking Prazosin.
• Avoid engaging in any hazardous tasks for at least 24 hours after taking the first dose, missing several doses, increasing the dose, or taking other high blood pressure medications.
• Before drinking alcohol, discuss it with your doctor.
• Patients who take medicine for high blood pressure often feel tired or run down for a few weeks after starting treatment. Be sure to take your medicine even if you may not feel "normal." Tell your doctor if you develop any new symptoms.
• Pregnancy and breast-feeding: If you become pregnant, contact your doctor. You will need to discuss the benefits and risks of using Prazosin while you are pregnant. Prazosin is found in breast milk. If you are or will be breast-feeding while you use Prazosin , check with your doctor. Discuss any possible risks to your baby.

Check with your doctor if any of these most common side effects persist or become bothersome:

• constipation; depression; dizziness; drowsiness; dry mouth; feeling of a whirling motion; flushing; frequent urination; headache; lack of energy; lightheadedness; nasal congestion; nausea; nervousness; nosebleed; stuffy nose; swelling; vomiting; weakness.

• severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision; fainting; pounding heartbeat; puffiness in hands or feet; rapid heartbeat.

Prazosin is to be used only by the patient for whom it is prescribed. Do not share it with other people.
If your symptoms do not improve or if they become worse, check with your doctor.