Silenor (Doxepin) – Oral

What Is Silenor?

Silenor (doxepin) is a prescription-only oral medication used for people with insomnia who have trouble staying asleep at night.

How Silenor helps with sleep is unclear, but it is thought to block histamine 1 (H₁) receptors. Histamine is a small molecule found throughout the body. It signals to the brain for you to stay awake. By blocking histamine receptors in the brain, Silenor causes you to feel drowsy.

Silenor belongs to a class of medications known as tricyclic antidepressants, which are medications named for their chemical structure. They have many uses, such as for depression and anxiety. Due to how this medication works, it should be taken 30 minutes before you go to sleep to make sure you get the most benefit.

Silenor is available in tablet form to be taken by mouth.

What Is Silenor Used For?

The Food and Drug Administration (FDA) approved Silenor to treat insomnia that is characterized by difficulty staying asleep.

How to Take Silenor

Always follow the directions given to you by your healthcare provider on how to take Silenor.

Generally, you will take Silenor on an empty stomach about 30 minutes before you go to sleep. Do not take this medication if you have had a meal within the last three hours, as it may delay the effects of the medication. Food slows the time required for this medication to reach its maximum level in the body, which may cause you to feel sleepy or drowsy in the morning.

Storage

Store Silenor in a cool, dry place. It can be stored between 59 and 86 degrees F. However, do not keep it anywhere it may be exposed to extremely hot or cold temperatures, like in your car or refrigerator. These environments can impact how well your medication works.

Do not freeze this medication. Keep it out of the reach of children and pets to prevent accidental consumption.

What Are the Side Effects of Silenor?

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the FDA at www.fda.gov/medwatch or 800-FDA-1088.

Common Side Effects

Common side effects that may occur while you are taking Silenor include the following:

• Drowsiness
• Nausea
• Upper respiratory tract infection
• Common cold
• Gastroenteritis (stomach flu)

Severe Side Effects

Notify your healthcare provider immediately if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

• Abnormal thinking and behavior changes
• Suicidal thoughts
• Worsening of depression

Call your healthcare provider immediately if you're experiencing depression or have any thoughts of suicide.

Silenor may also reduce fertility. It is unknown if the effects are reversible. Talk to your healthcare provider if this is a concern for you.

Long-Term Side Effects

Silenor does not have any documented side effects that have occurred after it has been stopped.

Dosage: How Much Silenor Should I Take?

Modifications

Consider the following before starting treatment with Silenor. Talk to your healthcare provider about how these factors may affect your medication.

Pregnancy

You should not take this medication if you are pregnant or planning to become pregnant. Studies have shown taking Silenor during the third trimester may increase the risk of a condition known as poor neonatal adaptation syndrome (PNAS).

Symptoms of PNAS may include the newborn feeling jittery/irritable or having difficulty maintaining body temperature, decreased muscle tone, and breathing problems.

Talk to your healthcare provider if you are pregnant or planning to become pregnant before starting Silenor. 

Breastfeeding

Silenor is known to pass through breast milk. It is not recommended to take Silenor if you are nursing due to the potential side effects it may cause in the baby (e.g., excess sleepiness and slowed breathing).

Children

The safety and effectiveness of Silenor in children have not been studied.

Adults Age 65 and Older

People 65 years or older may need to start on a low dosage of Silenor. Studies have shown similar safety and effectiveness in older adults compared to younger adults. However, the possibility of increased sensitivity in people of advanced age should not be ruled out completely. Medications that help promote sleep may cause increased confusion and sleepiness. 

Liver Damage

If you have liver damage, Silenor may have trouble breaking down in the body, leading to higher levels of the drug. It is recommended to start on a low dose if you have liver problems. Talk to your healthcare provider for more information about your treatment plan.

Kidney Damage

There are currently no studies of Silenor in those who have kidney damage. Since only a small amount of Silenor is removed through the kidneys, it is not expected that you will have higher concentrations of Silenor in the body if you have kidney damage.

Missed Dose

It is best to take this medication 30 minutes before you go to bed. Otherwise, if you miss your dose before bedtime, you can take it if you are having trouble falling asleep during the night. Skip the missed dose if you need to be awake soon, as Silenor can increase your drowsiness.

Overdose: What Happens If I Take Too Much Silenor?

The active ingredient, doxepin, is occasionally used at 10 to 50 times the dose of Silenor for other conditions.

Taking excessive amounts of Silenor (higher than 6 milligrams) may cause:

• Low blood pressure
• Constipation
• Indigestion
• Urinary retention
• Disorientation or hallucinations
• Numbness and tingling sensation
• Movement disorders, such as tremors, restlessness, and uncontrolled movements
• Seizures

These can be life-threatening issues and require hospitalization for proper management.  

Precautions

What Are Reasons I Shouldn’t Take Silenor?

Do not take Silenor:

• If you are allergic to its active ingredient, doxepin, or if you are allergic to any of its inactive ingredients
• If you are taking a medication class known as monoamine oxidase inhibitors (MAOIs) or have used an MAOI in the past two weeks. Using both medications together can cause dangerously high blood pressure. Examples of MAOIs include Zelapar (selegiline), phenelzine, and isocarboxazid
• If you have untreated narrow angle glaucoma or if you have severe urinary retention

What Other Medications Interact With Silenor?

Silenor is broken down in the body by an enzyme in the liver known as CYP450. Medications that block this enzyme may cause increased concentrations of Silenor in the body, which can enhance its side effects. Some examples of CYP450 inhibitors are:

• Biaxin XL (clarithromycin)
• Nizoral (ketoconazole)
• Zocor (simvastatin)

Tagamet (cimetidine), a medication used to treat stomach ulcers, is also broken down by CYP450. The use of cimetidine and Silenor together has been shown to double the concentration of Silenor in the body. If you must use these two drugs together, your healthcare provider may adjust your dosage.

Additionally, taking Silenor with the following may enhance its sedative effects:

• Alcohol
• Other central nervous system depressants, such as Valium (diazepam), Xanax (alprazolam), and phenobarbital
• Sedating antihistamines, such as promethazine

This is not a complete list of potential drug interactions. Before starting treatment, tell your healthcare provider about any other medicines you take or plan to take, including over-the-counter (OTC) nonprescription products, vitamins, herbs, supplements, and plant-based medicines.

What Medications Are Similar?

Silenor belongs to a broad class of medications known as tricyclic antidepressants. Tricyclic antidepressants are often used to treat symptoms of depression, and not all of them can be used for insomnia. In fact, certain tricyclic antidepressants can cause sleep difficulties as a side effect.

Examples of tricyclic antidepressants include:

• Elavil (amitriptyline)
• Pamelor (notriptyline)
• Tofranil (imipramine)

Other commonly used medications for sleep disorders include:

• Trazodone, an antidepressant, used for depression, anxiety, and insomnia
• Restoril (temazepam), a benzodiazepine, that treats short-term insomnia
• Ambien (zolpidem), a sedative-hypnotic drug, used for short-term insomnia relief

This is not a list of drugs recommended to take with Silenor. In fact, you should not take these drugs together. Talk to your pharmacist or a healthcare provider if you have any questions.

How Can I Stay Healthy While Taking Silenor?

It's important to take your medication exactly as directed by your healthcare provider. Additionally, maintaining a balanced diet, staying hydrated, and engaging in regular physical activity can help improve your overall health.

There are also healthy sleeping habits to practice. Try the following proper sleep hygiene measures:

• Avoid screens (e.g., phone, computer, TV) too close to bedtime.
• Set a consistent sleep schedule that you can stick with.
• Limit your bed use to sleeping.
• Avoid consuming caffeine or alcohol in the afternoon or evening.
• Set up a comfortable sleep environment in your bedroom.

The author would like to recognize and thank Cody Ryan Thomas for contributing to this article.