Doxylamine succinate is an antihistamine used in over-the-counter cold medications and nighttime sleeping aids, at doses of 25 mg or less. It is sometimes used in conjunction with decongestants to treat symptoms of the common cold. This drug can cause both minor and serious side effects.
Some antihistamines are used as sleeping aids. A main side effect of these drugs is drowsiness. Doxylamine succinate is found in some over-the-counter medications that make falling asleep easier. Avoid driving or operating heavy machinery when using a medicine containing doxylamine succinate. Alcohol consumption should also be avoided when using this drug -- drowsiness caused by this drug can be amplified by drinking alcohol.
Other Side Effects
Side effects of doxylamine succinate can affect many other body systems, including headache, dizziness, blurred vision, ringing in the ears, dry mouth, nausea, constipation, vomiting, difficulty urinating, and irregular heart rhythms. You may also experience central nervous system stimulation, such as nervousness, irritability and insomnia.
Serious Side Effects
Larger doses of doxylamine succinate than recommended are associated with more severe symptoms, including disorientation, tremors, convulsions and coma. Overdoses of doxylamine have been implicated in a condition called rhabdomyolysis, which causes rapid breakdown of skeletal muscle. Overdose may also cause kidney failure. Follow directions for use on the drug label to avoid overdose.
Avoid Use in Children
Safety of doxylamine succinate in children under the age of 12 has not been established. Children may be more sensitive to the nervous system effects of doxylamine and overdose may occur at lower doses than in adults. Generally, antihistamines should not be used as sedatives in children.
In addition to alcohol, antihistamines should not be taken with opioid analgesics or other drugs that affect the nervous system, such as anticholinergic or antimuscarinic medications, because of additive effects. Talk to a doctor or pharmacist about medications you are currently taking prior to using this over-the-counter medication. Pregnant or lactating women should consult a doctor before using doxylamine succinate -- nursing infants may have an adverse reaction to the antihistamine.