Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes Prazosin (Prazosin). If you are concerned about side effects, discuss the risks and benefits of Prazosin (Prazosin) with your doctor.

The following side effects have been reported by at least 1% of people taking Prazosin (Prazosin). Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• abdominal discomfort
• Constipation
• Diarrhea
• dizziness or lightheadedness, especially when rising from a lying or sitting position
• drowsiness
• Dry Mouth
• headache
• lack of energy
• nausea
• unusual tiredness or weakness
• vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• blurred vision
• chest pain
• fainting (sudden)
• frequent urge to urinate
• loss of bladder control
• pounding or irregular heartbeat
• signs of Depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• shortness of breath
• swelling of feet or lower legs

Stop taking the medication and seek immediate medical attention if any of the following occur:

• long-lasting (greater than 4 hours) and painful erection of the penis
• signs of pancreatitis (e.g., abdominal pain on the upper left side, back pain, nausea, Fever, chills, rapid heartbeat, swollen abdomen)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking Prazosin (Prazosin).

1 mg
Each capsule-shaped, peach, flat-faced with bevelled-edge tablet, scored and marked "APO P1" on one side, contains Prazosin (Prazosin) HCl equivalent to Prazosin (Prazosin) 1 mg. Nonmedicinal ingredients: croscarmellose sodium, D&C Yellow No. 10, FD&C Yellow No. 6, lactose, magnesium stearate, microcrystalline cellulose, and polysorbate 80.

2 mg
Each round, white, biconvex tablet, scored and marked "APO" over "P2" on one side, contains Prazosin (Prazosin) HCl equivalent to Prazosin (Prazosin) 2 mg. Nonmedicinal ingredients: croscarmellose sodium, lactose, magnesium stearate, microcrystalline cellulose, and polysorbate 80.

5 mg
Each diamond-shaped, white, biconvex tablet, scored and marked "APO" over "P5" on one side, contains Prazosin (Prazosin) HCl equivalent to Prazosin (Prazosin) 5 mg. Nonmedicinal ingredients: croscarmellose sodium, lactose, magnesium stearate, microcrystalline cellulose, and polysorbate 80.

Do not take Prazosin (Prazosin) if you are allergic to Prazosin (Prazosin) or any ingredients of the medication.

There may be an interaction between Prazosin (Prazosin) and any of the following:

• Aldesleukin
• Aliskiren
• alpha agonists (e.g., Clonidine, methyldopa)
• alpha/beta agonists (e.g., Epinephrine, norepinephrine)
• alpha blockers (e.g., Alfuzosin, Doxazosin, Silodosin, Tamsulosin)
• amifostine
• amphetamines (e.g., Dextroamphetamine, Lisdexamfetamine)
• angiotensin converting enzyme inhibitors (ACEIs; Captopril, Enalapril, Ramipril)
• angiotensin receptor blockers (ARBs; e.g., Candesartan, Irbesartan, Losartan)
• second generation anti-psychotics (e.g., Clozapine, Olanzapine, Quetiapine, Risperidone)
• barbiturates (e.g., butalbital, pentobarbital Phenobarbital)
• beta-adrenergic blockers (e.g., Atenolol, Propranolol, Sotalol)
• brimonidine
• calcium channel blockers (e.g., Amlodipine, Diltiazem, Nifedipine, Verapamil)
• decongestants (e.g., phenylephrine, Pseudoephedrine)
• diuretics (water pills; e.g., Furosemide, Hydrochlorothiazide, triamterene)
• Duloxetine
• Guanfacine
• levodopa
• Methylphenidate
• Minoxidil
• nitrates (e.g., Nitroglycerin, isosorbide dinitrate, isosorbide mononitrate)
• Obinutuzumab
• Pentoxifylline
• phosphodiesterase 5 inhibitors (e.g., Sildenafil, Tadalafil, Vardenafil)
• quinine
• Yohimbine

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Prazosin (Prazosin). Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use Prazosin (Prazosin).

Drowsiness/reduced alertness: Prazosin (Prazosin) can cause severe dizziness and lightheadedness. Avoid driving or operating dangerous machinery until you determine how Prazosin (Prazosin) affects you. Speak with your doctor if you experience severe dizziness or lightheadedness while taking Prazosin (Prazosin).

Kidney problems: If you have reduced kidney function, discuss with your doctor how Prazosin (Prazosin) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Prazosin (Prazosin), and whether any special monitoring is needed.

Orthostatic hypotension: Prazosin (Prazosin) has been known to cause severe dizziness and even loss of consciousness for people moving from a sitting or lying position to a standing position. This is known as orthostatic hypotension. It happens most commonly if the person is already taking another blood pressure-lowering medication, has just started treatment with Prazosin (Prazosin), or starts treatment with Prazosin (Prazosin) at a higher dose.

To help prevent this, get up slowly from a sitting or lying position. Your doctor will also recommend slowly increasing the dose of Prazosin (Prazosin).

Pregnancy: Prazosin (Prazosin) should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking Prazosin (Prazosin), contact your doctor immediately.

Breast-feeding: Prazosin (Prazosin) passes into breast milk. If you are a breast-feeding mother and are taking Prazosin (Prazosin), it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using Prazosin (Prazosin) have not been established for children under 12 years of age.

Seniors: Seniors may be more at risk of side effects such as dizziness and Low Blood Pressure.

Prazosin (Prazosin) belongs to the family of medications called antihypertensives, specifically the group known as alpha 1-blockers. It is used to treat mild-to-moderate high blood pressure. It relaxes blood vessels, allowing blood to flow through them more easily.

Prazosin (Prazosin) may be used alone or in addition to other medications to treat high blood pressure. Prazosin (Prazosin) may start working within 1 day, but it may take up to 14 days.

Prazosin (Prazosin) may be available under multiple brand names and/or in several different forms. Any specific brand name of Prazosin (Prazosin) may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of Prazosin (Prazosin) may not be used for all of the conditions discussed here.

Your doctor may have suggested Prazosin (Prazosin) for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking Prazosin (Prazosin), speak to your doctor. Do not stop taking Prazosin (Prazosin) without consulting your doctor.

Do not give Prazosin (Prazosin) to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take Prazosin (Prazosin) if their doctor has not prescribed it.