At 40 my skin is starting to sag. How do I look after it?

Skin that starts to feel looser around 40 reflects normal changes with age: the outer layer gets thinner and less stretchy, and the collagen and elastin fibres that support it are lost. Sun is a major contributor from outside. What you can do every day is protect your skin from the sun, not smoke, wash with mild soap and warm water, moisturise, sleep 7 hours or more, and see a dermatologist about any change that worries you.

Many people first notice it in photos or in the mirror under bright light: the jawline looks softer and the skin under the eyes looks thinner. This article explains what changes in skin with age, what speeds those changes up, and what daily care makes sense, based on the US National Institute on Aging (NIA), the US CDC and the UK's NHS.

Why does my skin start to sag around 40?

Skin changes in several ways as we get older, and some of these changes add up to the feeling that skin is less firm.

What changes with age

The NIA describes the changes like this:

For skin that starts to look tired around 30, see Skin looks tired at 30: where should you start?

Collagen and elastin in the skin

Collagen and elastin are fibres in the skin. The NIA explains that a loss of elastic fibres (elastin) and collagen causes skin to look older, develop wrinkles and become more fragile. When these fibres are lost, skin does not look as plump and smooth as it once did, which is part of why it can feel looser.

Hormonal changes around menopause

The NIA notes that hormonal changes, such as those that occur with menopause, can make skin thinner and drier. For many women this falls in the years after 40.

For loose skin after giving birth, see Loose skin after giving birth: how should I look after it?

What speeds up these changes besides age?

Age is something nobody can change. But several everyday factors add to it, and most of them are within your control.

Sun is a major contributor

The NIA calls the sun another major contributor to skin aging. UV light can damage skin cells, and over time the damage adds up, leading to changes in skin texture, premature skin aging and wrinkles. The NIA also advises avoiding tanning, including sunlamps and tanning beds. In Thailand, where the sun is strong almost all year, this includes daily exposure: walking to the BTS, waiting for a motorbike taxi, or sitting by a sunny window.

Smoking

The NIA lists smoking among things that can make skin feel dry and rough.

Dry air, hot water and too little to drink

The NIA lists drinking too little water, too much time in the sun and living in a dry environment among reasons skin feels dry and rough, and notes that hot baths and showers or too much soap can make dry skin worse.

What daily skin care makes sense at 40?

A simple routine you keep up every day matters more than many steps you only do now and then.

Protect from the sun every day

The NHS recommends a sunscreen with SPF 30 or higher and at least 4-star UVA protection. Apply it 30 minutes before going out and again just before, and reapply every 2 hours and after sweating. Do not forget the neck, ears and the backs of the hands. The NIA adds that UV rays can go through clouds, and suggests a hat with a wide brim, sunglasses that block 99% to 100% of the sun's rays, and loose, long-sleeved clothing when you plan to be in the sun.

Wash gently

The NIA suggests using mild soap and warm (not hot) water when bathing or showering.

Moisturise daily

The NIA suggests using moisturisers such as lotions, creams or ointments every day. If you sit in air conditioning all day, a small tube at your desk makes it easier. For skin that stings or reacts easily, see Sensitive, easily irritated skin: how do you care for it?

Be careful with products that promise to turn back time

The NIA advises being sceptical about products that claim to be anti-ageing, and suggests asking a dermatologist or your doctor which skin care products suit you. When you try a new product, introduce one at a time so you can tell what your skin is reacting to.

How should I eat and live day to day?

No food has been confirmed to make skin firmer. The habits below are for your health as a whole.

A healthy, well-balanced diet

In a Thai day, a balanced diet might look like:

Drink enough water

The NIA lists drinking too little water among things that can make skin feel dry and rough. Keep water to hand through the day, especially in hot weather and air conditioning.

Move most days

The NHS advises adults to do at least 150 minutes of moderate intensity activity a week, spread over 4 to 5 days or every day. A brisk walk in the cool of the evening, cycling, swimming or a dance class all count. Exercising outdoors early or late also means less midday sun.

Sleep 7 hours or more

The US CDC recommends 7 hours of sleep or more for adults aged 18 to 60, going to bed and getting up at the same time every day. For more on sleep and skin, see this article on short sleep and skin.

Do not smoke

If you smoke, stopping is one of the clearest steps you can take. A doctor or pharmacist can help you plan it.

When should I see a dermatologist?

Gradual softening of the skin with age is common. But see a doctor or dermatologist if:

• a mole has changed size, shape or colour
• a mole is painful, itchy, inflamed, bleeding or crusty
• you have a new or unusual mark on your skin that has not gone away after a few weeks
• your skin stays very dry or itchy even after weeks of gentle care
• a skin product or a medicine you take regularly seems to be affecting your skin

These signs for moles and marks come from the NHS. The NIA advises checking your skin often and seeing your doctor about any changes that worry you, and notes that some medicines can make skin more sensitive to sunlight.

If you want advice on how your skin is changing

A dermatologist can look at your skin type and how much sun you get, and suggest care that fits. If you take regular medicine, tell the doctor, and talk to a doctor or pharmacist before starting a new skin treatment or product. Do not stop or change a prescribed medicine on your own.

Skin at 40 changes for reasons that come with age. Daily sun protection, not smoking, sleep and gentle care are the parts you can look after every day.