Cough and cold medicines: codeine, dextromethorphan, decongestants and age limits

Match the product to the symptom

Dextromethorphan is an antitussive that temporarily relieves cough from colds or flu, but it does not treat the cause or speed recovery. Guaifenesin is an expectorant that thins mucus so it is easier to cough up. Pseudoephedrine is an oral decongestant for a blocked nose. Many products combine these with antihistamines or pain relievers.

Combination products are where errors happen. Two products can contain the same active ingredient, and taking them together can cause an overdose, so read every label before a patient adds a second product. Suppressing a cough that brings up large amounts of phlegm, or in asthma, emphysema or chronic bronchitis, deserves advice from a prescriber or pharmacist first. Ask about every product the patient is already taking, including night-time formulas and powders.

Codeine and dextromethorphan: antitussive risks

Codeine is an opioid, and its labels warn of addiction, misuse and serious breathing problems. Combining it with benzodiazepines, other depressants or alcohol can cause profound sedation, respiratory depression, coma and death. Codeine cough products are contraindicated in children under 12 and after tonsil or adenoid surgery under 18, partly because ultra-rapid metabolisers convert codeine to morphine quickly.

In the United States, prescription promethazine with codeine is indicated only for adults for cough. Teach patients to store codeine securely because it can harm others, especially children. Dextromethorphan should not be taken with an MAO inhibitor or within two weeks of stopping one, so ask about antidepressants and Parkinson's medicines such as selegiline.

Decongestants and the patient with hypertension

Pseudoephedrine is a sympathomimetic. Patients with high blood pressure, heart or thyroid disease, diabetes, glaucoma or difficulty urinating from an enlarged prostate should check with a prescriber or pharmacist before using it. Serious effects to report include nervousness, dizziness, sleeplessness and a fast, pounding or irregular heartbeat, and it also interacts with MAO inhibitors.

Check blood pressure and the medication list before recommending a decongestant, and suggest non-drug measures where appropriate. Advise taking the last daily dose several hours before bed to limit sleeplessness. NHS advice is that decongestant nasal sprays should not be used for more than a week, because longer use can make congestion worse. Older men with prostate enlargement may also find that decongestants make passing urine harder.

Age limits and teaching for parents

Over-the-counter cough and cold combination products can cause serious harm or death in young children. MedlinePlus advises not giving them to children under 4 and using caution with package directions from 4 to 11, and pseudoephedrine extended-release tablets are not for children under 12. NHS advice says decongestants should not be used by children under 6.

Age limits differ between countries and products, so follow the local label. Teach parents to use the measuring device supplied rather than a household spoon, to avoid giving two products with the same ingredient, and to offer fluids and rest. Honey is not for babies under one, and aspirin is not given to children and teenagers because of the risk of Reye's syndrome.

Apply it to an exam-style scenario

Consider a hypothetical parent who asks whether to give a 3-year-old a multi-symptom syrup containing dextromethorphan and pseudoephedrine, or a small amount of a grandparent's codeine cough syrup. Options include giving half the adult codeine dose, giving the over-the-counter syrup by weight, or advising against both and explaining comfort measures and warning signs.

Advising against both is correct. Combination products are not recommended under 4, and codeine is contraindicated under 12 because of the risk of serious breathing problems. Teach the parent to seek care for breathing difficulty, a very high temperature, symptoms lasting beyond about ten days or a cough lasting more than three weeks.

Sources and further reading

MedlinePlus: Dextromethorphan. Symptom relief without treating the cause, duplicate ingredients in combination products, under-4 age limit, MAO inhibitor interaction and phlegm or lung disease caution.

MedlinePlus: Pseudoephedrine. Cautions in high blood pressure, heart, thyroid and prostate disease, serious effects, bedtime timing, MAO inhibitors and paediatric age limits.

DailyMed: Promethazine hydrochloride and codeine phosphate oral solution. Contraindication under 12 and after tonsillectomy under 18, ultra-rapid metabolisers, adult-only indication, CNS depressant interactions and misuse risk.

NHS: Common cold. Decongestants not for children under 6, nasal sprays no longer than a week, honey and aspirin age limits, and when to seek medical help.