A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

Dextromethorphan and doxylamine is used to treat cough, runny or stuffy nose, sneezing, itching, and watery eyes caused by allergies, the common cold, or the flu. Dextromethorphan and doxylamine will not treat a cough that is caused by smoking, asthma, or emphysema.

Doxylamine may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• dry mouth, nose, and throat.
• drowsiness.
• nausea.
• increased chest congestion.
• headache.
• excitement.
• nervousness.

Toxicity. Doxylamine succinate is generally safe for administration to healthy adults. The median lethal dose (LD 50) is estimated to be ~500 mg/kg in humans. Symptoms of overdose may include dry mouth, dilated pupils, insomnia, night terrors, euphoria, hallucinations, seizures, rhabdomyolysis, and death.

Doxylamine, in doses of 25 and 50 mg., was found to be an effective hypnotic drug, with little difference in the performance of the two doses. Doxylamine performed generally better than secobarbital, 100 mg., but was somewhat inferior to secobarbital, 200 mg.

When they found her body, police also found three empty bottles of Unisom. Of the 96, they only found two stray pills in the car. The fourth bottle of sleep aid was never found. Toxicology tests later showed that Zhou died of overdosing on diphenhydramine – the active ingredient in the pills.

Can I take Unisom every night? Unisom is for occasional sleeplessness only. If your sleeplessness persists for more than two weeks, consult your doctor. Sleeplessness may be a symptom of serious underlying medical illness.

How long does Unisom® last? The sedative action of Unisom® may last up to 6 hours.

It’s also used for nighttime cold symptoms. Causing drowsiness is considered a side effect, but it can be a useful one for some people who need help getting to sleep or staying asleep. It shouldn’t be used for more than two weeks to treat insomnia.

Symptoms of overdose may include: large pupils, flushing, fever, hallucinations, weakness, shaking (tremor), muscle twitching, loss of consciousness, seizures. In children, excitement may occur first, and may be followed by loss of coordination, drowsiness, loss of consciousness, seizures.

Unisom Sleep Gels is only for short-term use until your symptoms clear up. Taking too much Unisom Sleep Gels can lead to serious heart problems, seizures, coma, or death.

Anxiolytics/sedatives/hypnotics (applies to doxylamine) resp depression. Oral anxiolytic, sedative, and hypnotic agents may cause respiratory depression and apnea when given in high dosages or following acute overdose.

Hepatotoxicity. Despite widespread use over many decades, doxylamine has not been linked to liver test abnormalities or to clinically apparent liver injury. The reason for its safety may relate its short half-life and limited duration of use.

The usual oral dose of doxylamine succinate as an antihistamine for adults and children 12 years and older is 7.5–12.5 mg every 4–6 h, not to exceed 75 mg within 24 h.