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Digital thermometers: what type to buy and how to take your temperature correctly

Need a way to check if you have a fever or potential COVID-19? We explain the pros and cons of different types of thermometer, where you can buy one and how to take your temperature accurately

Digital thermometers: what type to buy and how to take your temperature correctly

At a time when families are being encouraged to stay inside as much as possible to prevent the further spread of the novel coronavirus, COVID-19, a thermometer is a useful piece of kit to have to hand to keep tabs on your health.

Like many other such items though, they are selling fast as many people realise they don’t have one at home.

If you’re looking to buy a thermometer, we’ve rounded up our expert tips on choosing the best type, typical prices and how to use them properly.

We also have details on online stock availability from retailers including Argos, Boots and Superdrug.

The advice on this page is primarily aimed at adults wishing to take their own temperature. If you’re looking for advice on taking the temperature of babies or young children, see our guidance on how to take a baby or child’s temperature.

Types of thermometer: which is best?

If you’re shopping for a thermometer, you’ll find yourself having to decide between various types.

The cheapest isa basic digital thermometer that you hold under your tongue or underarm, but you can also get versions that take in-ear readings or no-contact options you point at your forehead. These tend to be more expensive.

Strip thermometers aren’t considered to be very accurate and the old mercury versions are also best consigned to history.

Here’s a quick run down of the pros and cons of the different types:

Digital thermometers (typically £5-10)

These are the most common type of thermometer and a good basic option. They should produce accurate readings when used correctly.

You can place the thermometer under your armpit, but you’ll get a more accurate reading from the mouth, where it should sit under the tongue.

The only real disadvantage is that it can be a bit uncomfortable to sit with it under your tongue for several minutes, and you’ll need to take care to clean it between uses.

You need to follow the instructions carefully too – usually they involve not having had a hot or cold drink or food for 30 minutes before taking your temperature, or having just come in from outside / done exercise, which can be quite restrictive.

Try to steer clear of old-style mercury thermometers – mercury is toxic and will be a pain to clean up if you end up breaking it accidentally.

Digital in-ear thermometers (typically £20-40)

Ear thermometers are quick and easy to use, taking just a few seconds to get a reading – using infrared technology to measure the temperature inside your ear.

You may get an inaccurate reading if the device isn’t positioned correctly in the ear, or if there’s a build-up of earwax.

They’re pricier than digital thermometers but might be a better option if you want a quick solution, or are trying to take the temperature of a child who doesn’t like to sit still for long. They aren’t recommended for newborns though.

Some use disposable probe covers which are convenient but an ongoing cost. Otherwise you’ll need to clean the ear probe between uses.

Non-contact thermometers (typically £30-70)

As the name suggests, with no-contact thermometers you don’t need to press the device against your skin or place it in your mouth. These thermometers use infrared technology to detect heat coming from the surface of your skin.

Non-contact thermometers tend to be more expensive, but if you’re looking for a non-invasive way to check a temperature, and want to avoid the faff of cleaning the thermometer between uses, they can be a good option.

Take your temperature using a smartphone

You can get a small plug-in device that, when hooked up to your smartphone via the headphone jack, turns it into a digital infrared thermometer.

To record a temperature, you simply place the gadget on your forehead or in your ear. Readings taken from the thermometer are fed into the smartphone app, which stores results so you can track changes over time.

See the Oblumi Tapp smartphone thermometer first look review for our first impressions of this tech. You can also see all our digital thermometer reviews.

What not to buy: forehead strip thermometers

These are appealingly cheap at £10 or less, and have some novelty value. You place them on your forehead and the strip changes colour to indicate temperature.

They’re cheap, but the NHS doesn’t recommend them as they measure the temperature of your skin, rather than your body. You’re better off using a digital thermometer to get an accurate reading from the armpit or mouth.

Buying a thermometer: who has stock?

Digital thermometers are one of the items that have been a victim of increased demand as the COVID-19 pandemic gathers pace.

As a result, most shops are running a slower-than-normal delivery service, while others have sold out of digital thermometers entirely. We had a quick check of major retailers:

  • Argos, John Lewis – Not currently available online
  • Asda – Two of the three digital thermometers are in stock, but delivery estimates go beyond a week.
  • Boots – Out of stock online. A message on the website promises that new stock is ‘coming soon’. It’s worth asking at the pharmacy in stores as some have may have stock. Like other essential items, they are limited to one per customer.
  • Superdrug – Out of stock.
  • Tesco – £20 inner-ear thermometer currently in stock.

Try asking at your local pharmacy as they may have stock or be able to tell you when stock is coming in

How to tell if you have a fever without a thermometer

Don’t panic if you can’t track down a thermometer. If you think you might have a fever the NHS suggests checking if the skin on your chest and back is hot to touch. This, along with feeling shivery, achey and generally unwell is a sign of fever.

How to take your temperature

Whatever type of thermometer you end up using, make sure you’ve cleaned it properly according to the instructions. This is usually done with cool, soapy water, but if you’re using an ear thermometer, use a dry cloth.

As different thermometers work in different ways, and getting it right affects the accuracy of the reading, it’s really important to always start by reading the manufacturers’ instructions, even if you’ve had a similar thermometer before.

If you have any further questions, consider asking a pharmacist.

  1. Tips for getting the best reading:

Fever aside, there are other factors that could affect the reading you get from a thermometer.

It’s worth checking it when you feel well, so you have an idea of what’s normal for you, as it can vary slightly.

If you’re checking your temperature multiple times a day to track progress of a fever, try to keep the conditions consistent. For example, excess clothing, bedding, having eaten or drunk recently, or outside weather conditions can all have an effect.

What is considered a ‘high’ temperature?

According to official NHS guidance, a ‘high’ temperature is considered as 38°C or over.

What is a fever?

According to the NHS, a fever is actually a process by which your body fights infections. It stimulates your immune system: your body’s natural defence. A fever makes it harder for the bacteria and viruses that cause infections to survive by increasing your body temperature.

How to treat a fever at home

Anybody can suffer from a fever, regardless of age. If you think you have a fever the best ways to help yourself recover are:

Be careful not to use flu remedies if you’re taking paracetamol and ibuprofen tablets as they usually contain these drugs too so it’s easy to take more than the recommended dose.

If you or someone in your family has a fever and you need advice, you can call NHS 111, or your GP.

Coronavirus symptoms

COVID-19 affects the lungs and airways and a fever and new cough are some of the key symptoms. Government advice is to stay at home if you show either of the following symptoms:

If you think you might have these symptoms, your first port of call should be the NHS 111 online COVID-19 tool.

Coping with coronavirus

If you believe you have the coronavirus infection, you’ll need to self-isolate to prevent it from spreading further. Do not go to a GP surgery, pharmacy or hospital. Ideally you shouldn’t leave your home at all, even to get food or medicine – see if someone can drop these off at your door instead.

For those that live alone, government advice says to stay at home for seven days from when your symptoms started.

If you’re living with others and are the first to show symptoms, the same rule applies. However, all the other people living under the same roof must stay home and not leave the house for a total of 14 days.

Bear in mind, as the UK is currently in lockdown, you shouldn’t be leaving your home for more than buying essentials, brief exercise or essential work/caring anyway.

For more advice on the symptoms of coronavirus, what to do if you think you have it and how to protect yourself and others from getting it, see our full guide – Coronavirus: how to protect yourself.

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