You may have a fairly good idea of what to do if someone breaks an arm, or even stops breathing, but could you spot the signs of poor mental health in a friend, relation or colleague? Mental health first aid is an idea that is taking hold, at a time when record numbers of people have been seeking help for mental health conditions. It’s not as straightforward as treating, for instance, a cut or a burn. Signs of depression and anxiety can be tricky to spot, says Stuart Payne, a mental health first aid trainer for St John Ambulance, which runs courses in workplaces. It can show up differently for everyone and “there’s no hard and fast rule on mental health”, he says. But there are common signs and symptoms that could indicate an issue. Here are some things to be aware of.

Look for behavioural change

This can be a key sign, says Payne. “If a person is normally the life and soul of the party, and all of a sudden they are reclusive or subdued, that would be enough for me to think it’s worth a check. If someone is normally quiet and reserved, then appears to excessively come out of their shell, while that doesn’t necessarily seem like a bad thing initially, it is still a behavioural change and worth double-checking how they are.” Changes can be subtle, he says. At work, absenteeism is a more obvious sign, but its opposite, presenteeism, is also common. Someone may be using work as a distraction from mental health problems, or be overcompensating if they are feeling guilty about not being as focused, says Payne.

Is someone withdrawing?

In a work situation, it could be that a person starts to eat lunch alone, says Payne. If that is unusual, it could be a sign of a problem. You may also spot it with your family or friends. Stephen Buckley, head of information for the mental health charity Mind, says: “If you meet as a group every week and play football or go running and one of the group drops out and there’s no reason why; or you notice someone is not responding to group chats or phone calls – withdrawing from social contact – it might be an indicator that they are not having a great time.”

Watch out for physical signs

“At the extreme end of the scale, it could be [evidence of] self-harm,” says Payne. But at work, he says, “People keep up a mask of professionalism.” Instead, signs that they are taking less care over their appearance, for example, could be a subtle reflection of their state of mind. “Sometimes, ironing your shirt or doing your hair is effort and someone going through major things in life might struggle with it.” You may notice someone losing or gaining weight, says Buckley. “Perhaps they are more irritable or angrier than you would expect. Perhaps you see they are drinking alcohol more or you are concerned that they are taking drugs more than they used to – if they have taken them in the past.”

Be aware of life situations

“These are not physical clues, but might be useful checking points,” says Buckley. “Obvious examples might be if someone has lost their job recently, a relationship has broken down, if there has been a bereavement, or other significant stress.”

Check in with the person

It doesn’t have to be a big, serious conversation, says Payne. “Just a general ‘How are things?’” Listen to what they are saying – or not saying. “We all use language differently. Some people might start to describe physical signs and symptoms: ‘I’m exhausted, I’m worn out.’ Others might find it easier to talk about the emotional side: ‘I’m sad, I’m upset.’ Or it could be a blend.” People may be reluctant to ask for help, or admit anything is wrong. “It’s trying to pick out what is beneath what the person is saying, but not jumping to conclusions.”

You don’t need to be a doctor or a mental health expert, says Buckley, to ask how someone is doing. Obviously, be sensitive – you don’t need to say that you have noticed their weight gain, or that they have stopped washing their hair – and how you talk to a colleague will probably be different from how you approach a friend, but it’s fine to express concern gently. “You might say, ‘I’m just a little bit worried about you – are things all right?’” says Buckley.

Be empathetic

It can be tempting, says Payne, when someone does start to open up, to share our own ordeals – but this can be unhelpful: “Just because we’ve both shared the same experience, it doesn’t mean we felt the same way.” Having empathy means you don’t have to have been through a divorce or bereavement, for example, in order to be supportive. “Once you have asked that question, be present to listen to the answer,” says Buckley. This means “not making assumptions, not necessarily giving someone advice” or offering your opinion.

Point them in the direction of help

“With physical first aid, people generally recognise their limits,” says Payne. If someone has a severe cut, you wouldn’t try to put stitches in it for them. So with mental health, “it doesn’t mean you’ve got to be a counsellor – that’s a profession, for which it takes years to qualify”. It’s about supporting the person and encouraging them to seek professional help, he says, perhaps asking, “‘How would you feel about counselling? How would you feel about seeing your GP? Group therapies, self-help?’” Many companies have an employee assistance programme, which can offer support with mental health. “Let the person take ownership of [the choice],” says Payne. “I would choose what would work best for me, which might not work best for everybody.”

In a situation where someone is seriously unwell, perhaps at risk of injuring themselves, or expressing suicidal thoughts, “Check what kind of formal support they have because some people might have a key worker or a crisis support team,” says Buckley. “Do they know where to get help, other than from you? Because as a friend, it’s a lot to take on someone who is expressing suicidal feelings. Point out things like emergency GP appointments, how to get to A&E, or contact Samaritans.” If they are in immediate danger, call an ambulance.

Try again at a later date

If you have tried to approach a friend out of concern for their mental health, don’t push it if they clearly don’t want to discuss it. “I’d probably say ‘I’m always here if you want to talk,’” says Payne. “Even if you have got the wrong end of the stick and the person is fine, it leaves the door open. Don’t be scared to go back and check in.”

• In the UK and Ireland, Samaritans can be contacted on 116 123 or email jo@samaritans.org or jo@samaritans.ie. In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. In Australia, the crisis support service Lifeline is 13 11 14. Other international helplines can be found at www.befrienders.org.