Doxepin Side Effects: A Complete Guide

Doxepin is a prescription medication that’s used to treat insomnia, depression and anxiety. It’s a well-known, widely-used and well-studied medication that’s been used for more than 50 years in the United States and abroad. 

As with all medications, doxepin can cause certain side effects. These side effects can range in severity based on a variety of factors, including the dosage of doxepin you’re prescribed by your healthcare provider.

Generally, side effects from doxepin are more common and more severe when this medication is used to treat depression or anxiety than insomnia. 

Below, we’ve listed the common and uncommon side effects of doxepin, as well as a range of potential interactions that can occur between doxepin and other medications. 

We’ve also explained how your risk of experiencing certain side effects from doxepin can vary based on whether you use this medication to treat insomnia or a condition such as depression or anxiety. 

Doxepin is a tricyclic antidepressant. It’s been in use since the 1950s and approved by the FDA for use as a treatment for depression and anxiety since the late 1960s. 

Originally, doxepin was used to treat mental health problems such as major depressive disorder (depression) and anxiety.

After extensive trials, researchers found that doxepin is also effective as a treatment for insomnia (difficulty sleeping) when used at a very low dosage.

Doxepin works by changing the level of certain neurotransmitters in your brain and body.

As we mentioned above, doxepin is prescribed to treat depression and anxiety, and also to treat sleep problems such as insomnia. The dosages of doxepin used to treat different conditions can vary, often by a significant amount. 

For example, to treat depression and anxiety, doxepin is typically prescribed at a dosage of 75mg to 150mg per day. For people with mild depression or anxiety, it may be prescribed at a lower dosage of 25mg to 50mg per day. 

In comparison, to treat insomnia, doxepin is typically prescribed at a much lower dosage of three milligrams to six milligrams per day. 

This large difference in dosage means that some side effects of doxepin may be more common in people who use this medication to treat depression or anxiety than in people who use a lower dosage of doxepin to treat insomnia.

Common Side Effects of Doxepin

Used to treat insomnia, the most common side effects of doxepin (affecting between one and 10 percent of people) include:

• Sedation/drowsiness

• Hypertension

• Gastroenteritis

• Nausea

• Nasopharyngitis, upper respiratory tract infection and other cold symptoms

Of these side effects, sedation/drowsiness is the most common, affecting between six and nine percent of doxepin users in clinical trials. Since doxepin is a sleeping pill prescribed specifically to treat insomnia, this side effect isn’t unexpected. 

Overall, side effects from doxepin are usually mild and uncommon when the medication is used to treat insomnia. In clinical trials of Silenor®, a sleep medication that contains doxepin, less than one percent of participants discontinued use of the medication due to side effects.

As a sleep-promoting medication, doxepin may cause mild impairment to psychomotor skills the morning after it’s taken. 

This is a common side effect of almost all sleeping pills. It’s worth noting that studies of doxepin tend to show that its effect on next-morning alertness are much milder than other, older sleeping pills, such as benzodiazepines. 

Sleeping Pills and Abnormal Nighttime Behavior

Although reports are very uncommon, doxepin and other prescription sleeping pills may cause certain abnormal thoughts or nighttime behavior.

Abnormal behaviors associated with sleeping pills include sleepwalking, waking up late at night to prepare food, talk to others or have sex and “sleep-driving” — operating a motor vehicle while not fully awake, often with amnesia. 

These behavioral changes are uncommon and may be more likely to occur if a hypnotic sleep medication is used in combination with alcohol or other drugs, or if the medication is used at a higher-than-normal dosage. 

If you experience any abnormal thoughts or behavior at night after using doxepin, talk to your healthcare provider immediately.

Depending on your experience and insomnia symptoms, your healthcare provider may adjust your dosage or prescribe other medication to treat your insomnia. 

Doxepin is prescribed at a relatively low dosage to treat insomnia. It’s prescribed at significantly higher dosages (typically in the 75 to 150mg range), to treat conditions such as depression and anxiety. 

At higher dosages, the potential side effects of doxepin are different to those that may occur in patients prescribed doxepin for insomnia.

Severe side effects may be more common, including a potential risk of suicidal thoughts.

Suicidal Thinking and Behavior

Analysis of antidepressants, including tricyclic antidepressants such as doxepin, indicates that these medications can increase the risk of suicidal thinking and behavior in children and young adults with depression.

Based on clinical trial data, this increase is most significant in adolescents and young adults in the 18-24 age range. 

Due to this increased risk, doxepin carries an FDA boxed warning stating that patients who are prescribed doxepin should be monitored and observed for any signs of suicidality, worsening of depression symptoms or abnormal behavior. 

If you’re prescribed doxepin and experience any suicidal thoughts or abnormal behavior, contact your healthcare provider for help immediately. If your symptoms are life-threatening, call 911 immediately for medical assistance.

This warning is not printed on low-dose doxepin medications designed to treat insomnia. Trials of low-dose doxepin have not resulted in any reports of suicide and have not found any abuse potential. 

Common Side Effects of High-Dose Doxepin

Used at a dose of 25mg to 300mg to treat depression and anxiety, common side effects of doxepin include:

• Dizziness

• Drowsiness

• Dry mouth

• Blurred vision

• Tiredness

• Weight gain

• Increased sweating

• Ringing in the ears

• Nausea and vomiting

• Constipation

• Increased or decreased sex drive

• Urinary retention (difficulty urinating)

• Gynecomastia (breast swelling) in men

Of these side effects, drowsiness is the most commonly reported. Most of the time, any increase in drowsiness from doxepin disappears over time with continued therapy. Other side effects may also subside over time. 

If you’re prescribed doxepin and experience persistent dry mouth, blurred vision, conspiration or urinary retention that doesn’t improve on its own, or if any of these side effects becomes severe, contact your healthcare provider as soon as possible to discuss adjusting your dosage. 

Doxepin may interact with other medications, including other antidepressants and a variety of medications used to treat fungal infections, cardiovascular health issues, diabetes and other conditions. 

Antidepressants

Doxepin has the potential to interact with other antidepressants, particularly monoamine oxidase inhibitors (MAOIs). Commonly prescribed MAOIs include selegiline, phenelzine, tranylcypromine and isocarboxazid. These medications may be sold under a variety of brand names.

If you’re currently prescribed a MAOI, or you’ve used any MAOI medications in the last 14 days, do not use doxepin.

Other antidepressants, including SSRIs, can interact with doxepin.

If you currently use an SSRI such as bupropion, duloxetine, fluoxetine, fluvoxamine, paroxetine, sertraline, or any other drug in this class, make sure you disclose this to your healthcare provider while discussing doxepin. 

Other Medications

Doxepin can also interact with a range of other medications. These include medications used to treat heartburn and other digestive issues, such as omeprazole and cimetidine.

To avoid any potentially dangerous drug interactions, make sure you tell your healthcare provider about any and all over-the-counter and prescription medications you use or have recently used if you are considering using doxepin. 

Alcohol

Drinking alcohol shortly before or after using doxepin may increase feelings of drowsiness and confusion.

Although drinking mild amounts of alcohol with doxepin is not deadly, doing so is not recommended due to the increased risk of drowsiness, fatigue and potential injury. 

Doxepin can help treat a range of conditions including insomnia and major depressive disorder. If you're still considering doxepin, read our doxepin FAQ which has expert answers about how this medication works.

You can also visit our online psychiatry platform if you want to learn more about depression and anxiety treatments available. Get your mental health treated today, don't wait.