Phentermine
- Phentermine – Patient Information
- What is phentermine?
Phentermine is a medicine that may be prescribed by a doctor as part of a structured weight-management programme for selected patients.
This medication is currently FDA approved. In our clinic we have had hundreds of patients successfully treated with this option. Although every patient is unique and whether this medication is correct for you depends on the consultation with our doctors who can give you individualised advice. The below is for information only, please contact us if you have any questions.
It belongs to a group of medicines known as *sympathomimetic amines* and works primarily by reducing appetite. This can help some patients reduce their food intake when combined with appropriate dietary and lifestyle measures.
Phentermine is not suitable for everyone. A doctor must assess your individual medical history, current medicines, health conditions and other relevant factors before deciding whether it is clinically appropriate.
- How does phentermine work?
Phentermine acts on the central nervous system and has stimulant-like effects. One of its main effects is to reduce appetite, which may make it easier for some people to follow a reduced-calorie eating plan.
The response to treatment varies between individuals. Phentermine should be considered as part of a wider weight-management approach rather than as a standalone solution.
Treatment should be accompanied by appropriate advice about nutrition, physical activity and sustainable lifestyle changes.
- Who may be considered for treatment?
Phentermine is not appropriate for everyone seeking weight loss.
If you are considering treatment, our doctors will review information including:
Your current weight, height and BMI
Your medical history
Your current medicines and supplements
Previous weight-management treatments
Your blood pressure and cardiovascular risk where relevant
Your mental health history where relevant
Pregnancy or plans to become pregnant
Any conditions that could make treatment unsuitable
* Any potential interactions with other medicines
The decision to prescribe is made individually by a doctor following an appropriate clinical assessment.
Completing an online consultation does not guarantee that medication will be prescribed.
- Who should not take phentermine?
Phentermine may not be suitable if you have certain medical conditions or take certain medicines.
Examples of circumstances requiring particular caution or where treatment may be unsuitable include certain cardiovascular conditions, uncontrolled hypertension, hyperthyroidism, glaucoma, pregnancy and breastfeeding, and a history of certain psychiatric or substance-use problems.
Phentermine may also interact with other medicines, including certain medicines used to treat depression and other medicines that affect the central nervous system.
This list is not exhaustive. Your doctor will assess your individual circumstances before prescribing.
Do not start, stop or change any medication without discussing this with an appropriate healthcare professional.
- How is phentermine taken?
If phentermine is prescribed for you, your doctor will provide specific instructions about how and when to take it.
You should take it exactly as prescribed and should not increase the dose yourself if you feel that it is not working.
If you miss a dose, follow the instructions provided with your prescription or contact your clinical team if you are unsure what to do.
Do not take more than the prescribed amount.
- How long is treatment continued?
Phentermine treatment is reviewed regularly.
Your doctor may consider factors including:
Your response to treatment
Any side effects
Changes in your weight and BMI
Your blood pressure and other relevant health measurements
Your adherence to the treatment plan
Any changes in your medical history or other medicines
* Whether continuing treatment remains clinically appropriate
Treatment may be stopped or changed if your doctor considers that continuing is no longer appropriate or safe.
- Possible side effects
Like all medicines, phentermine can cause side effects, although not everyone experiences them.
Because phentermine has stimulant-like effects, possible side effects may include:
Increased heart rate or palpitations
Increased blood pressure
Difficulty sleeping or insomnia
Restlessness or nervousness
Anxiety
Headache
Dry mouth
Constipation
Nausea or other gastrointestinal symptoms
Changes in mood
If you experience troublesome or persistent side effects, contact your clinical team for advice.
- When should I seek urgent medical attention?
Seek urgent medical attention if you develop symptoms such as:
Chest pain
Severe or persistent shortness of breath
Fainting or collapse
Severe or unusual palpitations
Severe agitation or significant changes in behaviour
Severe allergic symptoms, including swelling of the face, lips or throat or difficulty breathing
If you believe you are experiencing a medical emergency, call *999* or attend your nearest emergency department.
- Can phentermine be taken with other medicines?
Phentermine can interact with other medicines, so it is important that your doctor knows about *all medicines and supplements you take*.
This includes prescription medicines, medicines bought from a pharmacy or supermarket, herbal products and supplements.
In particular, tell your doctor if you take medicines for depression, ADHD, blood pressure, diabetes or any other long-term condition.
Never assume that a medicine or supplement is safe to combine with phentermine without checking first.
- Pregnancy and breastfeeding
Phentermine should not be used during pregnancy unless specifically advised by an appropriate healthcare professional.
If you become pregnant while taking phentermine, stop taking it and contact your doctor or healthcare professional for advice.
Tell your doctor if you are planning a pregnancy, think you may be pregnant or are breastfeeding.
- Alcohol and phentermine
Alcohol may increase or worsen some unwanted effects associated with phentermine, including dizziness, impaired judgement and other effects on the central nervous system.
Your doctor can advise you about alcohol based on your individual circumstances and other medicines you may be taking.
- Can I drive while taking phentermine?
Some people may experience dizziness, restlessness, difficulty concentrating or other effects that could affect their ability to drive or operate machinery.
You should understand how the medicine affects you before driving or performing activities requiring concentration.
Do not drive if you feel that your ability to drive safely is impaired.
- Does phentermine guarantee weight loss?
No.
Individual responses to weight-management treatment vary. Phentermine does not guarantee a particular amount or rate of weight loss.
The aim of treatment is to support sustainable weight management alongside appropriate dietary, physical activity and lifestyle measures.
Your doctor will review your progress and determine whether continuing treatment remains appropriate.
- What happens if I experience side effects?
If you experience side effects or have concerns about your treatment, contact our clinical team.
Your doctor may recommend:
Continuing treatment with appropriate monitoring
Adjusting or stopping treatment
Further assessment
Changing to another treatment option where clinically appropriate
* Seeking urgent medical assessment where necessary
Medication should not be altered or stopped without appropriate clinical advice unless you are experiencing a potentially serious reaction requiring urgent medical attention.
- How we assess suitability
Our doctors individually assess patients before prescribing.
This may involve reviewing your:
Medical history → Current medication → Allergies → Height and weight → BMI → Relevant health conditions → Previous treatment → Potential contraindications and interactions
Where further information is needed, we may contact you by telephone or arrange a further consultation.
If we do not have enough information to make a safe prescribing decision, medication will not be prescribed until the necessary information or assessment has been obtained.
- Ongoing support
Our approach is focused on more than medication alone.
Where appropriate, patients receive support with:
Healthy eating
Physical activity
Sustainable lifestyle changes
Weight-management goals
Monitoring and follow-up
Advice about potential side effects and safety
Patients can contact our clinical team if they have questions or concerns during treatment.
- Important information
Phentermine is a prescription medicine and is not suitable for everyone.
It should only be taken by the person for whom it has been prescribed and should never be shared with another person.
Keep medicines out of the reach and sight of children.
Always follow the instructions provided with your prescription and the accompanying patient information.
If you have any concerns about your treatment, please contact your healthcare professional.