Doxazosin for Night Terrors: What to Know

Key Takeaways

Doxazosin is typically used to treat high blood pressure and benign prostatic hyperplasia (BPH) but can be used off-label for the treatment of PTSD-associated night terrors.
If you use doxazosin for night terrors related to PTSD, you should take it at bedtime. This also helps reduce fall risk, as doxazosin can cause low blood pressure, which leads to lightheadedness, dizziness, and fainting.
Taking doxazosin may provide relief from PTSD night terrors, but make sure you take this medicine exactly as prescribed and inform your doctor of all your current medications to minimize the risk of unwanted adverse effects.

Doxazosin is a generic medication (also sold under the trade names Cardura and Cardura XL). Doxazosin belongs to a group of medications called alpha-blockers. This medicine is approved by the FDA to treat high blood pressure and benign prostatic hyperplasia (BPH) or an enlarged prostate gland.

One of the off-label uses of doxazosin includes the treatment of PTSD-associated night terrors. While doxazosin is not approved by the FDA to treat PTSD nightmares, healthcare providers can still prescribe doxazosin to treat PTSD-associated night terrors using their clinical judgments. Please continue reading to learn more about the use of doxazosin for nightmares.

How does doxazosin work?

Doxazosin belongs to a drug class called alpha-blockers, which relaxes the smooth muscles in the prostate gland and blood vessels (arteries and veins). Specifically, doxazosin targets alpha-1 receptors located on smooth muscles. Therefore, by relaxing the muscles in the bladder neck and prostate, doxazosin and other alpha-blockers can help relieve symptoms of an enlarged prostate (benign prostatic hyperplasia), such as difficulties with urination (frequency, urgency, pain with urination, weak stream, dribbling, and incomplete emptying of the bladder).

Additionally, doxazosin relaxes blood vessels. As a result, it’s easier for blood to flow through the arteries and veins in the body. Therefore, doxazosin is also used to treat high blood pressure.

Non-FDA approved (off-label) uses of doxazosin include treatment of pediatric hypertension, ureteral stones (stones in the ureters, the tubes that carry urine from the kidneys to the urinary bladder), and erectile dysfunction.

In addition to hypertension and benign prostatic hyperplasia (BPH), doxazosin is used off-label to treat night terrors in people with post-traumatic stress disorder (PTSD).

How does doxazosin treat PTSD-associated night terrors?

It is unclear how doxazosin works to relieve nightmares caused by PTSD. However, findings have provided theories regarding the relationship between doxazosin and its role in treating nightmares.

In the brain region called the prefrontal cortex of PTSD patients, there is high alpha-adrenergic activity affecting this brain region. This is believed to be attributed to the exaggerated fear response and terrors seen in PTSD patients.

As mentioned, doxazosin is an alpha-blocker that affects the alpha-1 receptors in the smooth muscle on the blood vessel walls and also the brain. By inhibiting the alpha-adrenergic activity in the brains of PTSD patients, doxazosin is believed to alleviate this exaggerated fear response in people with PTSD.

Is doxazosin the same as Flomax?

Doxazosin is not the same as Flomax, although both medicines belong to the same drug class, alpha antagonists or alpha-blockers.

Flomax is the brand name product for the generic medication tamsulosin. Tamsulosin is used for treating benign prostatic hyperplasia. Flomax has been more commonly linked to a complication called intraoperative floppy iris syndrome that can occur during eye surgery. The risk of intraoperative floppy iris syndrome is significantly lower with other alpha-blockers, including doxazosin.

Doxazosin is a generic medication (sold under brand names Cardura and Cardura XL). It is used to treat benign prostatic hyperplasia and high blood pressure. Doxazosin is also used for off-label treatment for night terrors or nightmares in people with PTSD.

How much doxazosin should I take for PTSD nightmares?

The usual starting dose of doxazosin for PTSD nightmares is 1 mg at night. This dose may be slowly increased to 4 mg at night based on response and side effects. Doxazosin doses as high as 8 mg have been used in clinical trials to alleviate PTSD-associated nightmares. This dose was well-tolerated during the 280-day study period.

Doxazosin comes in the form of 1 mg, 2 mg, 4 mg, and 8 mg immediate-release tablets and 4 mg and 8 mg extended-release tablets. Both forms are used to treat benign prostatic hyperplasia (BPH). However, only the immediate-release formulation should be used to treat high blood pressure.

Why do you give doxazosin at night?

If you are prescribed doxazosin for PTSD-related nightmares, you should take it at bedtime to help prevent night terrors during sleep. Doxazosin can cause low blood pressure. Therefore, nighttime dosing can help prevent dizziness, lightheadedness, and fainting, especially when going from sitting or lying to standing. Severe dizziness can increase the risk of falls. Taking doxazosin at night lowers the risk of these side effects.

What are the advantages of doxazosin vs prazosin?

Doxazosin and prazosin are both alpha-blockers that are used to treat high blood pressure and BPH. Both drugs are used off-label to treat PTSD-associated nightmares. However, doxazosin may have some advantages over prazosin. Doxazosin has a longer half-life compared to prazosin. Prazosin’s half-life is about 2-3 hours, while doxazosin’s half-life can be as long as 22 hours.

Doxazosin extended-release is also available as a formulation called gastrointestinal therapeutic system (GITS) designed to improve its absorption. This means doxazosin (extended-release form) is absorbed better from the gut and has a longer duration of action with once-daily dosing. For instance, regular doxazosin is typically started at 1 mg and titrated up gradually, while doxazosin GITS can be started at 4 mg once daily.

In summary, doxazosin may be preferred due to the drug’s longer half-life and better absorption with the GITS formulation. However, more studies are necessary to learn more about the role of doxazosin and other alpha-blockers in treating PTSD-related nightmares.

What are the disadvantages of doxazosin?

The disadvantages of doxazosin include side effects such as dizziness, weakness, fatigue, headache, fast heart rate, swelling, upper respiratory infections, and orthostatic hypotension (low blood pressure when going from a sitting or lying position to standing).

Rarely, doxazosin can also cause very serious side effects, including allergic reactions. You should seek emergency medical care if you develop signs and symptoms of an allergic reaction, such as skin rash, hives, itching, swelling, or trouble breathing. Doxazosin can also cause priapism (a painful or prolonged erection). Seek emergency medical care for a painful erection that lasts more than 4 hours.

How to take doxazosin for PTSD nightmares?

Before starting treatment

Tell your doctor if you are allergic to doxazosin, other alpha-blocker drugs, or any other medications.
Give your doctor a full list of your other drugs, including prescription drugs, over-the-counter medications, dietary supplements, and herbal products. Be sure to mention medications used to treat erectile dysfunction (ED), motion sickness, allergies, irritable bowel syndrome, ulcers, and Parkinson’s disease. This will help avoid possible drug interactions between doxazosin and your other medications.
Give your doctor a complete medical history. Tell your doctor if you have a history of angina (chest pain), low blood pressure after taking medications, prostate cancer, liver disease, kidney failure, heart failure, constipation, short gut syndrome, or blockage or narrowing of the intestines.
Tell your doctor if you are pregnant or nursing an infant with breast milk.

During treatment

Read the prescription label and patient information leaflet carefully. Take doxazosin exactly as prescribed. Do not change the dose or dosing frequency without talking to your healthcare provider.
Keep all your medical and lab appointments. Your doctor may want to change the dose of doxazosin based on your response.
Call your doctor for medical advice about side effects if they are severe or do not go away in a few days. Seek emergency medical care if you develop serious symptoms of an allergic reaction.
Tell your doctor if you notice a sudden drop in blood pressure with dizziness and lightheadedness after taking doxazosin. There is an increased risk of this occurring after the initial dose (first dose), in the first few days after initiating therapy, and if you are on combination therapy with other medications for high blood pressure. Get out of bed slowly. If you develop postural hypotension (low blood pressure), your doctor may reduce your doxazosin dose.
Take the medication regularly. If you miss a dose of doxazosin, take it as soon as you remember. But if it is almost time for the next dose, skip the missed dose and go back to your regular dosing schedule. Do not take a double dose or extra medicine to make up for a missed dose.
Call your local poison control center, provincial poison control center, or the national poison control center at 1-800-222-1222 in case of an overdose.

Taking doxazosin for night terrors associated with PTSD may provide relief but carries some risks. Make sure you take the medicine as prescribed to lower the risk of health complications from this medicine.

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