Doxepin: Uses, Dosage, Side Effects and More

If you’re struggling with depression, anxiety, insomnia or another issue affecting your mental health, you may have heard of the tricyclic antidepressant (TCA) doxepin. Doxepin is a popular depression medication as well as an effective treatment for lack of sleep and/or anxiety.

Here’s the thing: It’s probably not the first medication you were offered for these problems. TCAs are effective medications, but these days, they’re not really a first-line treatment for any of these conditions.

So why are you hearing about it now? What is doxepin, and what does it treat? The answers to these questions and guidance on doxepin dosages are all below.

What Is Doxepin?

Doxepin is a prescription tricyclic antidepressant used to treat various conditions ranging from major depressive disorder (MDD) to insomnia. It’s a commonly prescribed medication in the United States — first approved in 1969 and sold as a generic medication under a variety of brand names depending on its intended use.

In fact, there are many forms of this medication. Doxepin comes in oral tablets, capsules and liquid solutions, as well as a topical cream (used for hives only).

In the United States, doxepin is commonly sold as Silenor® for insomnia and Sinequan® for depression and anxiety. The topical form is sold under the brand names Prudoxin® Cream and Zonalon®, with many other names appearing in other countries.

Doxepin is a prescription-only medication, meaning you’ll need to speak to a healthcare professional to get a prescription before you can buy it. 

Doxepin Uses

Doxepin is used to treat a range of conditions. As a tricyclic antidepressant, it’s often prescribed to treat major depressive disorder and anxiety disorders.

This medication is also commonly used at much lower doses to treat insomnia and as a topical to treat certain skin conditions and, sometimes, hives.

Doxepin is an antagonist of the H1 and H2 histamine receptors. These receptors play a key role in the regulation of the body’s sleep-wake cycle, which is why, in 2010, the FDA approved the use of doxepin as a treatment for adults with insomnia. 

Doxepin is an effective treatment for long-term, chronic insomnia and short-term difficulty sleeping. Some studies of doxepin have shown that it’s particularly effective as a treatment for insomnia in people who frequently wake up after falling asleep. 

• A 2013 scientific review of doxepin as an insomnia treatment looked at several studies. It concluded that doxepin, at small doses of 3 milligrams and 6 milligrams, is well tolerated, non-habit forming and effective at managing both chronic and transient insomnia.

• A 2014 review of doxepin use by elderly people with difficulty sleeping also found that it was an effective treatment. Researchers noted that it “significantly reduced waking after sleep onset and increased total sleep time.” 

There’s also the skin irritation use of doxepin to mention. Topical doxepin, in cream form, treats itching caused by skin conditions like lichen simplex chronicus and atopic dermatitis.

Although it seems to have been largely phased out by more effective drugs, doxepin is also occasionally used to treat hives.

Doxepin Dosages

As mentioned above, doxepin is prescribed at various dosages to treat different conditions. It’s crucial to only use it as directed — if you’re prescribed doxepin, follow the dosage instructions provided by your healthcare provider. 

The amount of doxepin contained in each medication can vary. For instance, the dosage of doxepin used to treat major depressive disorder is significantly higher than the typical dosage for insomnia.

For mild depression or anxiety, doxepin may be prescribed at a lower dose, sometimes as low as 25 to 50 milligrams. When prescribed for major depressive disorder, anxiety and other chronic conditions, it’s typically used at a higher dosage, often 75 to 150 milligrams per day.

The maximum doxepin dosage used for major depressive disorder and anxiety is 300 milligrams per day.

Doxepin Dosage for Sleep 

It’s important to note that doxepin is prescribed in significantly higher doses for depression and anxiety than for insomnia.

Doxepin is typically prescribed for insomnia at a dosage of 3 to 6 milligrams per night. Interestingly, the medication appears to be effective even at a very low dose.

In the 2014 review mentioned above, researchers concluded that there were no significant differences in effectiveness between the 3-milligram and 6-milligram doses of doxepin. 

A 2007 study even found that doses of doxepin as low as 1 milligram were effective at increasing total sleep time, reducing waking after sleep onset and improving sleep efficiency. People with insomnia who used doxepin slept longer, were less likely to wake up after falling asleep and typically experienced increased levels of sleep efficiency. 

FDA trial data shows that serious side effects from doxepin are uncommon when the medication is used at the 3- to 6-milligram dosage prescribed for insomnia. 

Doxepin Side Effects

Doxepin is generally considered a safe and effective medication. But like most tricyclic antidepressants (and prescription drugs, for that matter), it comes with a list of possible side effects you should be wary of

Doxepin can cause certain adverse effects. The most common side effects of doxepin include:

• Drowsiness, sleepiness and sedation

• Upper respiratory tract infections

• Nausea

A word on sleep and drowsiness: 

The sleep-inducing effects of doxepin last several hours after you take the medication. This means that although doxepin doesn’t cause next-day tiredness when used normally, it might make you feel drowsy if you only sleep for a short period.  

To avoid daytime drowsiness, only use doxepin to treat insomnia if you plan to sleep for seven to eight hours immediately after taking the medication. 

Doxepin can cause serious side effects in rare cases, including: 

• Constipation

• Worsening or blurred vision and eye pain

• Anxiety

• Suicidal thoughts

• Mania and behavioral changes

• Dry mouth

• Drops in blood pressure

• Cardiovascular risks, including changes to heart rate or heart rhythm

• Urinary retention

• Weight gain

• Changes to blood sugar levels

In extreme cases, people who take this medication may experience trouble breathing or an allergic reaction. If you think you’re experiencing these severe side effects, seek immediate medical advice.

If you forget to take doxepin, don’t take the missed dose and continue on as normal. Instead, skip that dose and return to your normal schedule.

It’s possible to overdose on doxepin. However, the dosage of doxepin prescribed to treat insomnia is less than 5 percent of the maximum recommended dosage for this medication.

If you’re concerned you or someone you’re with has taken an unsafe amount of doxepin, call your local emergency number or the national toll-free Poison Control hotline at 1-800-222-1222 as soon as possible.

Doxepin Interactions

Like other tricyclic antidepressants, doxepin has the potential to interact with other medications.

Several drugs are known to interact with doxepin, including some classified as major drug interactions. 

Common medications that can interact with doxepin include certain MAOIs (monoamine oxidase inhibitors) and SSRIs (selective serotonin reuptake inhibitors). If you use an MAOI or have used one within the last two weeks, taking doxepin may cause severe side effects.

You should generally not use doxepin alongside other antidepressants at all. This includes medications that affect your serotonin neurotransmitters, like fluoxetine, duloxetine, citalopram, paroxetine and fluvoxamine, as well as MAO inhibitors like selegiline, phenelzine and tranylcypromine.

To avoid any potential drug interactions, it’s essential that you disclose all other medications you currently use to your physician before using doxepin. 

Also, tell your doctor if you use medications specifically, including cimetidine, sertraline and quinidine. And let them know if you’re breastfeeding or have glaucoma or heart conditions. Additionally, doxepin shouldn’t be taken for bipolar disorder.

Other medications that can potentially interact with doxepin include sleeping pills, narcotic pain medications, anxiety medications and medications used to treat seizures. You should absolutely let your healthcare provider know about any over-the-counter sleep aids you use before taking doxepin. 

Doxepin shouldn’t be combined with alcohol. Drinking alcohol after taking doxepin can result in increased feelings of drowsiness and reduced concentration, creating an elevated risk of injury or accident. 

How Long Does It Take for Doxepin to Work?

One of the most important things you need to remember when taking doxepin is to take it on the right schedule. For antidepressants, this typically means taking it once daily at bedtime or divided up into two or three smaller doses taken throughout the day.

For insomnia, doxepin should be taken at least three hours after consuming a meal and within 30 minutes of going to bed. After taking doxepin, limit your activities to those necessary to prepare to go to sleep. 

Doxepin has a half-life of 15 hours, meaning each dose of the medication will be halfway eliminated from your body after roughly 15 hours. A single 6-milligram dose of doxepin will reach its peak concentration approximately three and a half hours after consumption. 

Doxepin: Final Takeaways

Doxepin may or may not be your secret to improved mental health or better sleep. That’s a decision only your healthcare provider can make with you. We’re just here to give you some information to make that choice effectively. 

Considering a switch to doxepin? Here’s what to keep in mind:

• Doxepin is a tricyclic antidepressant — a type of antidepressant medication that treats anxiety and insomnia.

• If you find it difficult to get enough sleep, or find yourself waking up frequently during the night, doxepin could be an effective treatment option to help you manage your insomnia and benefit from longer, higher-quality sleep. 

• However, this medication may cause more serious side effects than other antidepressants, and it might conflict with other medications more seriously.

• There are other ways to treat depression, anxiety and certain causes of insomnia. Consider online therapy, and check out our full antidepressant list and guide to anxiety medication for more information. 

Want doxepin? Want answers to more of your questions? We can help. We offer online psychiatry and other mental health services from the comfort of your home.