A dry cough is a cough where no phlegm or mucus is produced (known as non-productive). A dry cough is irritating and usually associated with a tickly throat. Dry coughs are often caused by viral illnesses such as colds and flu, but they can also be caused by allergies or throat irritants.
Specific treatment for a dry cough will depend on the cause of the cough.
How long does a cough normally last?
Coughs associated with a cold or the flu tend to last a week or 2, most clearing up within about 3 weeks. A post-viral cough may persist for several (up to about 8) weeks after a viral illness, while some coughs persist for longer and are usually a sign of an underlying problem.
In adults and children, a cough is described as acute (short term) if you have been coughing for up to 2 weeks.
In adults, a cough that lasts for more than 8 weeks is described as a chronic (ongoing) persistent cough.
In children, a cough that lasts 2 to 4 weeks is called a prolonged acute cough. A cough that lasts more than 4 weeks is considered to be a chronic cough.
Causes of dry cough
A dry cough is often the result of:
- a viral illness, such as a cold or influenza (the flu), or COVID-19 the disease caused by SARS-CoV-2 – the novel coronavirus; or
- a post-viral, or post-infective, cough (cough that persists for weeks after a viral illness).
However, a dry cough may be a result of other problems, such as:
- gastro-oesophageal reflux;
- allergic rhinitis (hay fever) due to inhaling substances you are allergic to, such as pollen, dust or pet dander;
- post-nasal drip (the drainage of mucus secretions from the nose or sinuses down the back of the throat – also known as upper airway cough syndrome);
- laryngitis (inflammation of the larynx, also known as the voice box);
- whooping cough;
- obstructive sleep apnoea and snoring;
- habit cough (a cough that is only present in the daytime and not caused by illness – it most often affects school-aged children);
- an inhaled foreign body (e.g. food or other objects accidently being inhaled – usually in babies and small children);
- certain types of lung disease known as interstitial lung disease; or
- a side effect from a medicine (for example, cough is a possible side effect of most ACE inhibitors – often prescribed for high blood pressure).
Other, less common, causes of a dry cough include:
A dry cough can be aggravated by:
- breathing cold, dry air;
- air pollution;
- inhaled irritants such as dust or smoke;
- exposure to tobacco smoke;
- excessive use of your voice; or
- a change in temperature.
A persistent dry cough can cause problems, including the following complications.
- Repeated coughing can lead to urinary incontinence in women, especially older women, pregnant women and those who have been pregnant.
- Interrupted sleep resulting in tiredness is a common problem for people with a persistent cough.
- Severe or uncontrollable coughing fits can sometimes cause vomiting.
- Headaches may result from a persistent cough.
Can I hurt myself coughing?
When a cough is severe, pulled chest muscles and even fractured ribs are a possible complication.
Diagnosis and tests
Your doctor will ask about your cough and any other symptoms you may have, and perform a physical examination. Depending on your age, history and examination, your doctor may order tests such as:
- a chest X-ray;
- a throat swab (sample of secretions from the back of your throat which can be tested for infections);
- lung function tests; or
- allergy tests.
Dry coughs are often related to a viral illness and in most cases special tests are not needed.
When should you seek medical advice about a dry cough?
You should you seek medical advice if:
- you start to cough up blood or copious amounts of mucus (phlegm);
- you are short of breath or wheezy;
- the cough is mainly at night;
- you have associated chest pain;
- you have a fever;
- you are a cigarette smoker;
- you have a hoarse voice;
- the cough is associated with vomiting or a choking sensation;
- you have other symptoms such as an ongoing headache, sore ears or a rash;
- you have recently lost weight or have general muscle aches;
- the cough is in an infant aged 6 months or younger;
- the cough has lasted longer than 10 days, with little or no improvement; or
- you have high blood pressure, a heart complaint, respiratory illness (such as asthma), gastrointestinal problems or are taking other medicines.
Treatments for dry cough
Dry coughs that are caused by a viral infection such as a cold usually get better on their own within a week or two. Self-help measures can help make you feel better in the meantime, and cough medicines may provide some short-term relief to adults with a dry cough.
Other treatments for dry cough will depend on the cause.
Self-help for dry cough
There are some simple things you can do to provide relief from a dry cough.
Honey can help treat a dry cough by coating and soothing the back of the throat (pharynx), and relieving the irritation that triggers a dry cough. Try drinking warm water containing honey and lemon, or taking one to 2 teaspoons of honey 30 minutes before bedtime. Note that honey should not be given to children younger than 12 months of age due to the risk of infant botulism (a rare bacterial infection).
Drinking plenty of liquids can help, and warm broths or teas may help soothe your throat.
Gargling salt water (in older children and adults) may also help with a dry cough associated with a cold and sore throat.
Dry cough can be a side effect of some medicines such as ACE inhibitors and beta blockers (used to treat high blood pressure and heart problems). Your doctor may recommend stopping any medicines that could be causing your cough and replacing them with other suitable medicines for your particular condition. Talk to your doctor about alternative medicines if you are having this problem.
Repeated coughing from any cause can irritate and inflame the larynx (voice box) and upper airways. So the coughing itself makes your airways more sensitive, leading to more coughing. Strategies that can help you reduce the urge to cough and help stop this type of self-perpetuating cough include:
- taking a sip of water with a hard swallow when you feel like coughing or clearing your throat; and
- avoiding any triggers that you know tend to aggravate your cough, such as overuse of your voice, cigarette smoke, or excessively cold, dry air such as from air conditioning.
Cough suppressants, sometimes known as antitussives, can sometimes be used for the short-term treatment of dry coughs in adults. Cough suppressants work by suppressing the urge to cough, and include any of the active ingredients pholcodine, dextromethorphan, codeine, dihydrocodeine, and pentoxyverine. They are available as:
- lozenges (which may also contain an antibacterial to help soothe a sore throat); or
- liquid or linctus (cough mixture).
Some cough suppressants need a prescription, while others are available from pharmacies without a prescription. Possible side effects of cough suppressants include drowsiness, nausea, vomiting, and constipation.
Some combination cold and flu medicines – available as tablets or liquid – may contain cough suppressants. Cold and flu combination medicines may also include:
- an antihistamine (antihistamines that have sedative effects may help if your dry cough is disrupting your sleep – your doctor may recommend you take these medicines before bedtime);
- a decongestant (to relieve a blocked or stuffy nose); and
- paracetamol for relieving pain and fever.
Always take care to check the active ingredients in any combination product. If you take a combination product and then also take additional medicines, you risk doubling up on ingredients. For example, added paracetamol may lead to an overdose of paracetamol if other paracetamol products are also being taken. If you have a dry cough, you should avoid taking combination products that contain an expectorant or a mucolytic, as these ingredients are used to treat productive (‘wet’ or chesty) coughs.
Cough and cold medicines (including cough suppressants, antihistamines and combination medicines) should not be used in children younger than 6 years of age, and should only be used in children aged 6 to 12 years after checking with your doctor or pharmacist. These medicines have not been shown to be effective in children, and there is some evidence that they can cause harmful side effects.
Nasal sprays and inhalers
If your doctor suspects that hay fever (allergic rhinitis) or post-nasal drip (when mucus runs down the back of your throat) may be causing you to cough, a saline nasal spray and a corticosteroid nasal spray may be recommended.
A corticosteroid inhaler, where the medicine is breathed in through your mouth, may be recommended by your doctor if asthma is a possible cause of your dry cough.
People with gastro-oesophageal reflux disease (where acidic stomach contents flow back up your oesophagus) sometimes have a persistent cough or a choking-type cough at night. Treating the reflux with acid blocking medicines (such as proton pump inhibitors) can help relieve a cough caused by reflux. Self-help measures for treating reflux (such as not eating just before bedtime and tilting up the head of your bed) can also help.