Is doxepin like an antihistamine?

What is doxepin?
Doxepin is a tricyclic antidepressant.

Doxepin capsules and oral concentrate (liquid) are used to treat symptoms of depression and/or anxiety associated with alcoholism, manic depression, or other mental illness.

Doxepin tablets (Silenor) are used to treat insomnia in people who have trouble staying asleep.

This medication guide provides only information about doxepin capsules and liquid.

Doxepin may also be used for purposes not listed in this medication guide.

Source and more info:
https://www.drugs.com/mtm/doxepin-capsules-oral-concentrate.html

What is doxepin topical?
Doxepin is a tricyclic antidepressant. When applied to the skin, doxepin topical can help relieve itching but it will not treat symptoms of depression.

Doxepin topical (for use on skin) is used to treat itchy skin in adults with eczema or other skin conditions that can lead to repeated scratching and thickened skin.

Doxepin topical may also be used for purposes not listed in this medication guide.

Source and more info:
https://www.drugs.com/mtm/doxepin-topical.html