Sinequan (doxepin hydrochloride) is part of a group of anti-depressants called tricyclic antidepressants (TCAs), it's role is to increase the effects of neurotransmitters by blocking their reuptake. The exact mechanism of action of Sinequan is not known, but the hypothesis is that the clinical effects may be due to preventing norepinephrine reuptake into the nerve terminals at the synapse level. Doxepin has a strong local anesthetic action and like all other antidepressants it has a sodium channel blocking activity.Sinequan is prescribed in the treatment of:1. Psychoneurotic patients with depression and/or anxiety2. Depression and/or anxiety associated with alcoholism3. Depression and/or anxiety associated with organic disease (interaction with other drugs should be considered)4. Depressive disorders with associated anxiety including manic-depressive disorders.5. Chronic pain from a variety of conditions, eg. fibromyalgia, chronic headache or migraineSymptoms that respond particularly well to Sinequan include anxiety, tension, depression, sleep disturbances, insomnia, guilt, lack of energy, fear, apprehension and worry.Clinical experience has shown that Sinequan is safe to use and and well tolerated. Although some of the newer anti-depressants can have fewer side effects than the tricyclics, individuals will respond differently to particular treatments and the response may also vary over time. The type of treatment will depend on many factors, including the type of depression, other medications a patient is taking, the presence of other medical conditions, and a patient's response to previous therapy.Side effects are usually most common when first starting the treatment, and should be reported to your health care professional if they do not clear up or worsen.Common Sinequan side effects include: constipation or difficulty urinating (more likely in the elderly), dizziness (try standing slowly), drowsiness (problems with fatigue may be reduced by taking Sinequan in the evening or at bedtime), dry mouth, sensitivity to sunlight , temperature sensitivity, or weight gain.Occasional Sinequan Side Effects: blood sugar changes, dental cavities, fainting, headache, hives, increased appetite, indigestion, nausea, rash, shaking, swollen face or tongue, unsteadiness, weakness. Getting up slowly may prevent dizziness rising from a sitting or lying position. If this condition worsens you should contact your doctor. Sinequan is best taken with food in most cases, to prevent indigestion and nausea.Rare side effects: brown or red spots on skin, change in sense of taste or hearing, irritated tongue or mouth, nightmare, sexual side effects (impotence, difficulty with orgasm), sweating, restless feeling, vomiting.Advise your doctor if you are pregnant or plan to become pregnant, or if you are breastfeeding, as Sinequan's effects on unborn babies and nursing infants has not been established.Some medications should not be mixed with Sinequan at all, and with others your doctor may want to adjust your dose to decrease the risk of adverse side effects. Make sure your doctor is aware of all the medications and supplements you are taking, as well as any other medical condition you may suffer from.