How do smoking, diabetes and certain medicines delay fracture healing? The risk factors that affect bone repair, and the practical steps patients can take to support their recovery.
On this page 7 sections
Smoking is one of the most important risk factors for slow bone healing, and one that is within your own control. In people who smoke, fractures take longer to unite, and nonunion, wound-healing problems and infection are all more common. Poorly controlled diabetes, alcohol, poor nutrition, vitamin D deficiency and the long-term use of certain medicines can delay healing in a similar way. The good news about smoking and bone healing is that many of these factors can be improved even after a fracture has happened, and doing so makes a real contribution to recovery.
This article explains how smoking, diabetes and some medicines affect bone, what you can do in practice to reduce these risks and when you should see a doctor. The aim is not to blame anyone, but to help patients understand the part they can play in their own treatment.
Smoking and bone healing: what happens in the body?
For a broken bone to heal, the area needs a good supply of blood, oxygen and repair cells. Smoking interferes with almost every step of this process:
- Nicotine narrows blood vessels, reduces blood flow to the fracture and slows the growth of new vessels.
- Carbon monoxide binds to haemoglobin in the blood, lowering the amount of oxygen delivered to the tissues.
- Other chemicals in tobacco smoke suppress the bone-forming cells (osteoblasts) and weaken the immune response.
Studies show that in smokers fractures take longer to heal, the risk of nonunion is clearly higher and problems with wounds and deep infection after surgery are more frequent. This matters particularly for shin bone fractures, for corrective operations in which the bone is cut and realigned, and for long treatments such as limb lengthening.
E-cigarettes, heated tobacco and shisha
These products are often seen as gentler alternatives, but most contain nicotine, and nicotine itself has harmful effects on blood flow and bone cells. Shisha can also expose the user to large amounts of carbon monoxide. There is not enough evidence to regard any of these products as harmless for bone healing.
Is it too late to stop?
No. Within a few days of stopping, carbon monoxide levels in the blood fall, and over the following weeks circulation and tissue oxygen levels begin to improve. Stopping after a fracture is therefore still worthwhile. If you are due to have planned orthopaedic surgery, stopping several weeks beforehand is generally advised. Support makes success more likely, so speak to your doctor or a local stop-smoking service. If you are thinking of using nicotine replacement products, discuss this with the doctor in charge of your treatment.
Practical steps to make stopping easier after a fracture
- Set a quit date and remove cigarettes, lighters and ashtrays from your home.
- Tell your family and friends about your decision, and ask people not to smoke in the house.
- Note the moments that trigger the urge to smoke, such as after meals, with tea or coffee, or when stressed, and plan new habits for them.
- Boredom while your movement is restricted can make cravings stronger, so structure your day with the exercises and activities your doctor allows.
- A single cigarette does not mean you have failed; carry on from where you left off and ask for support again if you need it.
Diabetes and fracture healing
High blood sugar impairs the work of bone-forming cells, the production of collagen and the growth of new blood vessels. Long-standing diabetes can damage small blood vessels and nerves, which affects both the blood supply to the fracture and the healing of wounds. People with diabetes also have a higher risk of infection after surgery. In addition, reduced activity, pain, stress and changes in eating habits after a fracture can make blood sugar less stable, so you may need to check it more often and stay in closer contact with your diabetes team during this period.
When nerve damage (neuropathy) is present, pain is felt less, so a broken leg may be overloaded without the person realising it. For this reason, people with diabetes who break an ankle may need a longer period of protection and restricted weight-bearing. Swelling, redness and warmth in the foot without much pain can be a sign of Charcot foot, a condition that it is important to recognise early.
- Monitor your blood sugar and your three-month average (HbA1c) regularly, and review your treatment with your GP, diabetes team or endocrinologist.
- Do not change your diabetes tablets or insulin doses without medical advice.
- Check the edges of your cast or splint and your feet every day, and report any wound, redness or discharge straight away.
Medicines that can affect bone healing
The long-term use of some medicines can affect bone metabolism. These medicines are usually treatments you need, however, and this information does not mean you should stop taking them. In such cases doctors weigh up the risks and benefits together.
- Long-term steroid (corticosteroid) treatment: can reduce bone formation and contribute to osteoporosis.
- Some anti-inflammatory painkillers: their effect on bone healing is debated, and whether short-term use is appropriate is decided by your doctor.
- Chemotherapy and medicines that suppress the immune system: can affect cell renewal and resistance to infection.
- Some epilepsy medicines: can interfere with vitamin D metabolism and so affect bone health indirectly.
Important: never stop a medicine or change its dose without talking to your doctor. Bringing a list of all the medicines and supplements you take to your orthopaedic appointment helps your treatment to be planned properly.
Alcohol, nutrition and other risk factors
- Alcohol: regular heavy drinking suppresses bone-forming cells, disrupts nutrition and increases the risk of further falls and fractures.
- Nutrition: bone repair needs enough energy and protein. Poor nutrition, especially in older people and those with a reduced appetite, can delay healing.
- Vitamin D and calcium: vitamin D deficiency is common and impairs bone mineralisation. Levels should be checked, and supplements taken if needed, on medical advice.
- Osteoporosis: even when fractures heal, implants used for fixation may grip less securely, and treatment may be needed to prevent further fractures.
- Other conditions: chronic kidney disease, narrowed arteries, rheumatic conditions and excess weight can also affect healing.
When several of these factors are present together, healing problems become more likely. To find out more about the causes of nonunion and what influences treatment outcomes, see our article on factors that influence the outcome of nonunion surgery.
Risk factors at a glance: what can be done?
| Risk factor | How it affects healing | What can be done |
|---|---|---|
| Smoking and nicotine products | Reduces blood flow and oxygen supply, suppresses bone-forming cells | Stopping, with help from stop-smoking services |
| Diabetes | Impairs cell and blood vessel function, raises infection risk | Blood sugar control, foot and wound care, regular follow-up |
| Long-term steroids | Can reduce bone formation | Not stopping on your own; joint planning between your doctors |
| Alcohol | Harms bone cells and nutrition, increases fall risk | Cutting down or stopping |
| Poor nutrition and low vitamin D | Reduces the building blocks needed for repair | A balanced, protein-rich diet and supplements on medical advice |
Addressing these risk factors is as important as the mechanical support provided by surgery. In nonunion treatment, too, the surgical plan goes hand in hand with improving these biological conditions; for more detail, see our article on biological and mechanical approaches in nonunion surgery.
When should you see a doctor?
Particularly if you smoke, have diabetes or take long-term medication, see a doctor if you notice:
- pain at the fracture site that persists or worsens after the expected healing time
- a feeling of movement, "giving" or clicking at the fracture
- redness, discharge or opening of a surgical wound, or a fever
- unexplained swelling, redness and warmth in the foot if you have diabetes
- new numbness, a change in skin colour or a limb that looks increasingly bent
If healing appears to have stalled, examination, imaging and blood tests are used to find out whether the cause is mechanical, biological or related to infection. Treatment options are described on our nonunion surgery and complex and infected nonunion pages.
Key points
- Smoking slows bone healing by reducing blood flow and oxygen delivery, and raises the risk of nonunion and infection.
- It is never too late to stop: stopping after a fracture or before surgery still helps.
- Poorly controlled diabetes, alcohol, poor nutrition and vitamin D deficiency can all delay healing.
- Some medicines affect bone metabolism, but none should be stopped without medical advice.
- Correcting these risk factors is as much a part of recovery as surgical treatment.
Frequently Asked Questions
Yes. The effects of nicotine and carbon monoxide on blood flow and oxygen delivery occur even with a small number of cigarettes. Cutting down can be a step in the right direction, but for bone healing the goal is to stop altogether. If you find stopping difficult, you do not have to do it alone: stop-smoking services can help you choose suitable support, in discussion with your doctor.
For planned orthopaedic surgery, stopping smoking several weeks beforehand is generally advised, and the longer you stop for, the more your circulation and tissue oxygen levels improve. Even if surgery is only a short time away, stopping still brings benefits, such as a fall in carbon monoxide levels in the blood. The ideal timing depends on the type of operation and your health, and should be discussed with your surgeon and anaesthetist.
No. Most fractures in people with diabetes do heal. However, if blood sugar is poorly controlled, healing may be slower and wound problems and infection become more likely. After a fracture it is therefore important to monitor your blood sugar regularly, take good care of your feet and any wounds, and follow weight-bearing advice carefully. Your treatment plan is made in cooperation with the doctor who looks after your diabetes.
The effect of some anti-inflammatory painkillers on bone healing is still debated, and the evidence is not conclusive. Which painkiller to use, and for how long, is therefore decided by your doctor according to the type of fracture, your risk factors and any other health problems. Good pain control also matters, because it allows you to move and take part in rehabilitation. Rather than choosing medicines yourself or stopping a prescribed one, ask your doctor.
In people whose vitamin D levels are low, correcting the deficiency helps to provide the conditions bone needs to heal. In someone whose level is already normal, however, there is no strong evidence that extra supplements speed up healing, and unnecessary high doses can cause unwanted effects. It is therefore sensible to have your vitamin D level checked and, if needed, for your doctor to recommend a suitable supplement.
This article is for general information only and does not replace a medical examination, diagnosis or treatment. Treatment options and outcomes vary from person to person.
Related treatment area Revision Surgery for Complex and Infected Nonunion
