A Cold: What Actually Shortens It, and What Is Just Being Sold to You

Almost nothing shortens a cold. That is the honest headline, and everything sensible follows from accepting it.

A cold runs seven to ten days, with a cough that outlasts it by a week or two. The available interventions make you more comfortable while your immune system does the work — which is a genuinely worthwhile goal, and a different one from cure. An entire supermarket aisle exists to blur that distinction.

So: what helps you feel better, what does not work, and — the part that matters — how to tell a cold from the things that are not a cold.

The shape of a normal cold

Knowing the shape prevents most unnecessary worry and most unnecessary antibiotics.

Days 1–2: sore or scratchy throat, sneezing, tiredness. Days 3–5: the streaming, congested worst of it. This is the peak, and it is meant to feel like this. Days 5–7: mucus often turns thicker and yellow or green. This is not a bacterial infection and it is not a reason for antibiotics. It is what happens as immune cells clear up, and it is the single most common reason people ask for a prescription they do not need. Days 7–10: mostly better. Weeks 2–3: a lingering cough, which is normal. Our lingering cough page covers when it is not.

Children get more colds and longer ones — six to eight a year in a preschooler is normal, and back-to-back colds through a school year are why one winter can feel like continuous illness.

What genuinely helps

Rest, and permission to take it. Not because activity prolongs a cold, but because you will feel considerably better and sleep is when the immune work happens.

Fluids. Enough to keep urine pale. Dehydration makes every symptom worse and thickens the mucus.

Saline — nasal spray or rinse. One of the few genuinely effective things. It clears mucus mechanically with no side effects, it works for children, and it is cheap. Use distilled, sterile or previously boiled water for a rinse, never straight tap water.

Steam or a humidifier, for comfort.

Honey for a cough, over the age of one. Performs about as well as most cough syrups. Never under one — infant botulism.

Acetaminophen or ibuprofen for aches, sore throat and fever. Dose by weight for children. Never aspirin for a child or teenager.

Warm drinks and salt-water gargles for a sore throat.

Zinc has modest evidence for shortening a cold if started within about 24 hours. It tastes unpleasant, causes nausea in some people, and interacts with some medicines. Never use a zinc nasal product — there are reports of lasting loss of smell.

Sleeping propped up helps a night-time cough and blocked nose.

What does not work

Said plainly, because the money involved is considerable.

Antibiotics. A cold is a virus. Antibiotics do nothing to it, they cause diarrhoea and rashes, and every unnecessary course makes the bacteria you carry more resistant. The green mucus on day five is not the signal, and this is the most persistent misunderstanding in primary care.

Vitamin C does not prevent colds. Decades of study, stable answer. It may very slightly shorten one if taken continuously beforehand. Taking it once you are ill does essentially nothing.

Echinacea and elderberry: evidence weak or absent.

Most combination cold and flu remedies treat several symptoms you may not have, at doses set for an average nobody is. If you want to treat a symptom, treat that symptom.

Over-the-counter cough medicines do little for anyone and are not suitable for young children. Honey is better and safer.

Decongestant nasal sprays work well and only for about three days. Longer than that produces rebound congestion — a blocked nose caused by the spray itself, which is a genuinely difficult cycle to break. Saline has no such limit.

And a real caution on decongestants: the oral kind raises blood pressure and heart rate. If you have high blood pressure, heart disease, or take medication for either, ask us before taking one — this is one of the most common ways a controlled blood pressure quietly stops being controlled.

Cold weather does not cause colds. Neither does wet hair or a draught. Viruses cause colds, and they spread in winter because we go indoors together.

When it is not a cold

• A sore throat with fever and NO cough or runny nose points at strep, which is bacterial and does need treating. Our sore throat page covers it
• Sudden onset, high fever, body aches, and flattening exhaustion is flu rather than a cold — and there is a 48-hour window where antiviral treatment is most useful. Our flu page leads with it
• Itchy eyes, sneezing, clear runny nose, no fever, and the same time every year is allergy. Very commonly treated as repeated infection here, because the local calendar is not the national one
• Facial pain, pressure and congestion that worsens after day ten, or improves and then clearly worsens, suggests sinusitis
• Ear pain after a cold — our ear infection page
• A cough lasting more than three weeks needs assessing rather than waiting out
• In Arizona: a cough with fatigue going on for weeks may be Valley fever, a fungal infection that no antibiotic touches and that is regularly found only after two or three courses have failed

Call us if

• Symptoms that improve and then get worse again. The most commonly waited-out sign of a second infection on top of the first
• A fever above 102°F, or any fever lasting more than three days
• Any fever in a baby under one month — an emergency at any hour
• Difficulty breathing, wheeze, or breathing that looks like hard work
• Chest pain, or pain on breathing
• Not drinking, or no urine in eight hours
• Severe sore throat, difficulty swallowing, or drooling in a child
• Ear pain
• A cough lasting more than three weeks
• Anyone with asthma needing their reliever more than usual, COPD, a weakened immune system, or a serious chronic condition
• Confusion or unusual drowsiness, particularly in an older adult — that can be how a serious infection presents rather than a cold

Reducing the spread

Handwashing, and soap and water rather than gel for stomach bugs — norovirus is not killed by alcohol sanitiser.

Cough into your elbow.

Stay home while feverish, and for children, until fever-free for a full day without medicine.

You are contagious before you feel ill, which is why this spreads so well and why none of the above is a personal failing.

Do not share cups, bottles or utensils — the hardest one in a household with children.

Get the flu shot. It does not prevent colds and it prevents the illness people most often mistake for one.

Sources

26. Common cold — MedlinePlus Medical Encyclopedia, U.S. National Library of Medicine. https://medlineplus.gov/ency/article/000678.htm

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