Doxepin

What is doxepin?

Doxepin belongs to a group of medicines called tricyclic antidepressants. In the past, these medicines were commonly used for depression, but today doctors usually prescribe newer classes of antidepressants. Tricyclic antidepressants are used for severe depression or when other antidepressants are unsuitable. Read more about antidepressants.

In New Zealand doxepin is available as capsules in different strengths – 10 mg, 25 mg and 50 mg.

Dose

• The dose of doxepin will be different for different people.
• Your doctor will usually start you on a low dose and increase this slowly. This allows your body to get used to the medicine and reduces side effects.
• Doxepin is usually prescribed as a single dose to be taken at bedtime, although your dose may be different.
• Always take your doxepin exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much doxepin to take, how often to take it, and any special instructions.
• If your capsules look different to your last supply, ask your doctor or pharmacist for advice.

How to take doxepin

• Take doxepin at the same times each day. It is usually taken as a single dose at bedtime, but your dose may be different.
• Swallow your doxepin capsules with a glass of water.
• You can take doxepin with or without food.
• If you forget to take your dose, take it as soon as you remember. But, if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.
• Keep taking doxepin every day. It may take a few weeks before you notice the full benefits of doxepin.
• If you think doxepin is not working for you, do not stop taking it suddenly; speak to your doctor or nurse before stopping.

Precautions – before starting doxepin

• Have you recently had a heart attack?
• Do you have problems with your heart rhythm?
• Do you have diabetes?
• Do you have problems with your kidneys or liver?
• Do you have problems with your thyroid?
• Do you have glaucoma?
• Do you have bipolar disorder?
• Do you have epilepsy?
• Do you have problems passing urine or problems with your prostate?
• Do you have problems with constipation?
• Are you pregnant or breastfeeding?
• Are you taking any other medicines, including medicines you can buy without a prescription, such as herbal and complementary medicines?

If any of these apply, it’s important that you tell your doctor or pharmacist before you start doxepin. Sometimes a medicine isn’t suitable for a person with certain conditions, or it can only be used with extra care.

Precautions – while taking doxepin

• Alcohol: avoid alcohol while you are taking doxepin, especially when you first start treatment. Drinking alcohol while taking doxepin can cause drowsiness and affect concentration, putting you at risk of falls and other accidents. It can also cause agitation, aggression and forgetfulness. If you do drink alcohol, drink only small amounts and see how you feel. Do not stop taking your medication.
• Diabetes: if you have diabetes, you may need to check your blood glucose more often because doxepin can affect the levels of glucose in your blood. 

Possible side effects

Like all medicines, doxepin can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Suicidal behaviour

The use of antidepressants has been linked with self-harm or suicidal thoughts and behaviour. Children, teenagers, young adults and people with a history of suicidal behaviour are most at risk. This is most likely during the first few weeks of starting treatment or if the dose is changed. It is important to look out for signs of suicidal behaviour such as suicidal thoughts, self-harm, worsening of low mood, agitation or aggression.

If you notice any of these signs, contact your doctor immediately. If you need urgent help or are concerned, phone:

• Lifeline 0800 543 354 (available 24/7), or
• Healthline 0800 611 116, who can give you the phone number for your local mental health crisis line.

Other side effects

Interactions

Doxepin interacts with many other medications and herbal supplements (such as St. John's Wort) so check with your doctor or pharmacist before starting doxepin or before starting any new medicines.

Learn more

The following links have more information on doxepin.

New Zealand Formulary Patient Information: Doxepin

References

1. Doxepin New Zealand Formulary
2. The role of medicines in the management of depression in primary care BPAC, 2017