All surgery carries a degree of risk, and before having an operation to reduce or increase your breast size, make your nose or tummy smaller, or any other procedure, it's important to be fully aware of these, and consider whether any individual lifestyle factors and pre-existing health conditions may affect the level of risk involved.

"Cosmetic surgery is a growing industry, but organising it isn't as simple as just calling up and booking yourself in," says Professor Marcos Sforza, an aesthetic surgeon at MyAesthetics. "In some cases, you're making the decision to have the equivalent of a major operation, which means thorough research is required."

"A cosmetic surgery practice should never try to rush you into a choice, or try to pressurise decision-making through last-minute discounts or deals," says Sforza, who adds that: "If you're thinking of undergoing a procedure, it's essential you're healthy and understand the risks associated with the surgery you're thinking about."

Here, Sforza outlines five key health considerations for anybody thinking about pursuing cosmetic surgery...

1. Being a healthy weight

"Bear in mind that excess weight could put the body under more strain and at risk of certain side-effects and complications from surgery," says Sforza. Being overweight also increases the likelihood of sleep apnoea, where people stop breathing repeatedly during sleep. This can complicate the administration of general anaesthesia, and anyone prone to it should tell their surgeon.

Cosmetic surgery results are generally best if your body mass index (BMI) is under 30, and Sforza advises: "If you're told by your doctor that your weight might impact the results of your surgery - and the circumstances aren't pressing - think about losing weight under a doctor's supervision. Improving your health before surgery will make it as safe as possible, minimise chances of complications and quicken your recovery." Weight loss should be stabilised at least six months before surgery.

2. Allergies

It's imperative to inform your surgeon of any known allergies, because some dressings contain ingredients you may be sensitive to, such as acrylates, silicones, rubber and latex.

And it doesn't have to be a major allergic reaction to be worth mentioning - telling medical staff about any minor past reactions, such as irritations caused by silver or nickel in jewellery, bra clips or watch straps, can be useful, as it will help your surgeon build an accurate picture of how your body may respond to potential allergens. "Most allergic reactions aren't serious but can be uncomfortable," notes Sforza, who says that sometimes extra treatment, such as topical corticosteroids or antihistamines, may be required.

3. Cigarettes and alcohol

Smokers will need to quit before surgery, and for a some time afterwards. Nicotine causes blood vessels to compress - and smaller blood vessels can reduce blood supply to organs and tissues, slowing wound healing. Also, smokers can be at higher risk of complications, says Sforza. Patients are advised to stop smoking completely for six weeks before and six weeks after surgery, and abstain from all nicotine-containing products too.

In addition, cutting out alcohol one to two weeks before surgery is generally recommended, because of possible interactions with anaesthesia and increased risks of bleeding. It's important to discuss any recreational drug use with your surgeon too, as this can increase anaesthetic risks.

"Just be honest, and your surgeon will discuss with you the best way forward to guarantee the best possible outcomes of your surgery," says Sforza.

4. Pre-existing health conditions

Your surgeon will also need to know relevant things about your general health, including any other conditions you have, or are being treated for. Two common examples are asthma and diabetes.

Any heart or respiratory conditions must be reported, stresses Sforza. If you're scheduled for treatment, asthma needs to be well-controlled beforehand to reduce the possibility of a flare-up before or during surgery. Get a check-up with your doctor at least a week beforehand, so you know you're in the best possible health. Those with more acute asthma may need to take inhaled bronchodilators or corticosteroids, or steroids by mouth before surgery to manage symptoms better.

As for diabetes - the better controlled it is, the better your chances of an excellent surgical outcome, stresses Sforza. Keeping your blood glucose within the recommended parameters is vital, as is first-rate nutrition. If you're diabetic, hyperglycemia (high blood glucose) or hypoglycemia (low blood glucose) could be an issue post-procedure and wound healing could be slower.

And tell your surgeon about any other medications you're taking, even if not regularly, because they could have side-effects that need to be considered.

5. Mental health

Nerves, sleep deprivation and recovery, which may involve some pain, lethargy and swelling, can be both physically and emotionally draining, so it's essential you prepare yourself as best you can. "Surgery can be intimidating for anyone," advises Sforza. "After all, in some cases it's equal to a major operation, so even the most organised of us can feel apprehensive in the build-up."

Patients who've experienced mental health issues in the past may be asked to complete psychological screening prior to any surgery. This is just a precaution, so there's a second professional opinion on how well you recognise the implications of surgery, and the potential impact of any unanticipated outcomes.