The Independent Pharmacy

Appetite Suppressants, Why They’re Bad For Weight Loss And Alternatives

Scott McDougall
Scott McDougallMPharmDirector & Registered Manager

Reviewed on 16 Aug 2023

Our data shows appetite suppressant popularity is on the rise after recent celebrity endorsement — despite the potential dangers of these unregulated supplements.

Google Trend data shows peak popularity for searches around ‘best appetite suppressants’ in England mid-last month and further Google data shows there were more searches year-on-year in June for ‘appetite suppressants’ and ‘best appetite suppressants’.

However, the fact remains that appetite suppressants are not a prescribed medicine. The supplements sold over the counter to suppress appetite are unregulated and potentially dangerous. There is also no medical or clinical data to show they work, despite any qualitative endorsement.

There are many supplements sold as suppressants like Ketone, DNP, Matcha, Acai — some with brand names like “fat buster” and “fat burner” — but none of these are medicines, regulated and approved by the MHRA (Medicines & Healthcare products Regulatory Agency).

There are many unwanted side effects to suppressants, and unregulated suppressants are potentially dangerous.

Here we look into appetite suppressants in more detail — including why they are not a safe way to manage your weight loss. We’ll also give you some safer weight loss alternatives to consider.

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The history of appetite suppressants

Appetite suppressants used to be prescribed to people with a body mass index (BMI) of 30 or above, or for those with a BMI of 27 or higher if they have other obesity-related risk factors (type 2 diabetes and high cholesterol). They were not designed to be taken for any longer than a year.

But, they have experienced a fall from grace in the past decade and are no longer available on prescription. We at The Independent Pharmacy recommend that unregulated ones are avoided — there are plenty of horror stories of people buying dodgy diet pills online.

Reductil’s fall from favour

Reductil was a popular appetite suppressant that contained the active ingredient sibutramine hydrochloride monohydrate. This medicine was discontinued in the UK in 2010. A review by the European Medicines Agency suggested a link between taking Reductil and an increased risk of non-fatal strokes and heart attacks.

These risks outweighed the weight-loss benefits achieved with this medicine. People who were taking Reductil were advised to consult with their doctor for alternative weight loss treatments.

How do appetite suppressants work?

Appetite suppressants act on neurotransmitters in the brain. These transmitters are natural chemicals found in nerve cells, which are released from the nerve cells when a neural message is transmitted. Neurotransmitters are then reabsorbed into the nerve cells upon the successful transmission of the message.

Appetite suppressants block two of these neurotransmitters from being reabsorbed into the nerve cell. These are noradrenaline and serotonin. These chemicals are responsible for regulating mood and various other processes.

Preventing these chemicals from being reabsorbed, results in more noradrenaline and serotonin acting in the brain. This has the effect of enhancing the feeling of being full post-eating. This allows you to feel satisfied for longer after actually consuming less food.

Why appetite suppressants are potentially dangerous

Now that they are no longer available on prescription, you might consider buying appetite suppressants online, but it’s a risky route to take.

There are many supplements sold as suppressants like Ketone, DNP, Matcha, Acai, some with brand names like “fat buster” and “fat burner”. However, none of these are medicines, and there is no proof that they actually work.

There are many unwanted side effects to suppressants, and unregulated suppressants are potentially dangerous.

People who suffer from any of the following should avoid appetite suppressants:

  • Epilepsy
  • Depression
  • Decreased kidney function (mild to moderate)
  • Decreased liver function (mild to moderate)
  • Hypertension (high blood pressure)
  • Sleep apnoea
  • Family history of Glaucoma (open-angle)
  • Family history of motor or verbal tics (recurrent muscle twitches and vocalisations)
  • People who take anticoagulant medication, such as Warfarin.

Appetite suppressants SHOULD NOT be used by those:

  • Who are over 65 years of age
  • Who are under the age of 18
  • Who suffer from obesity caused by a medical condition
  • Who have severely decreased kidney function
  • Who have severely decreased liver function
  • Who have uncontrolled hypertension (high blood pressure)
  • Who have a history of coronary artery disease
  • Who is suffering from heart failure
  • Who suffer from tachycardia (increased heart rate)
  • Who suffer from arrhythmias (irregular heartbeats)
  • Who suffer from and have a history of strokes
  • Who suffers from the peripheral arterial occlusive disease (blocked arteries in the extremities)
  • Who suffer from glaucoma (closed-angle)
  • Hyperthyroidism (overactive thyroid)
  • Phaeochromocytoma (a tumour in the adrenal gland)
  • Who have urinary retention
  • Who have Tourettes
  • Who suffer from or have a history of anorexia
  • Who suffer from or have a history of bulimia
  • Who suffer from or have a history of alcohol or substance abuse
  • Who are pregnant or breastfeeding
  • Who suffers from rare hereditary problems, such as galactose intolerance
  • Who have recently taken antipsychotics, antidepressants or appetite suppressants to help with insomnia (difficulty sleeping).

Appetite-suppressant side effects

Appetite suppressants can potentially cause side effects. Medicines and their side effects affect different people in different ways. The following side effects are known to be associated with appetite suppressants.

However, because a side effect is listed here, it does not mean that everyone who takes appetite suppressants will experience all, if any, of these side effects:

  • Insomnia
  • Dry mouth
  • Diarrhoea, constipation
  • Nausea and vomiting
  • Headache
  • Paraesthesia (pins and needles)
  • Excessive sweating
  • Depression
  • Anxiety
  • Palpitations
  • Lightheadedness
  • Hypertension (high blood pressure)
  • Impotence
  • Seizures
  • Hot flushes
  • Aggravation of haemorrhoids (piles)
  • Thrombocytopenia (platelet reduction in the blood)
  • Kidney disorders
  • Menstrual cycle disorders
  • Alteration in taste

Appetite suppressants with other medicines

Before you start any new treatment, you should always inform your doctor or pharmacist of the medicines you are currently taking, including those bought over-the-counter and any herbal treatments.

Appetite suppressants can interact with other medicines, making them potentially ineffective, even dangerous. They should not be taken at the same time as, or within 2 weeks of any of the following medications:

  • Monoamine oxidase inhibitors
  • Antidepressants
  • Antipsychotics
  • Tryptophan
  • Other appetite suppressants

Appetite suppressants should not be used at the same time as other medicines that increase serotonin levels in the brain. Doing so may result in a side effect called serotonin syndrome, which can be serious.

Medicines that increase the brain’s serotonin levels include:

  • Lithium
  • Antidepressants such as selective serotonin reuptake inhibitors (SSRIs)
  • Antimigraine medicines such as dihydroergotamine or any of the triptan family
  • Opioid painkillers such as fentanyl, pethidine, dextromethorphan, pentazocine, and tramadol
  • Herbal remedies such as St John’s Wort.

The following medicines can increase the risk of experiencing the side effects associated with appetite suppressants:

  • Ketoconazole and itraconazole (antifungals)
  • Erythromycin and clarithromycin (antibiotics)
  • Ciclosporin

The following medicines can decrease the effectiveness of appetite suppressants:

  • Antiepileptics
  • Dexamethasone
  • Rifampicin

You should consult your doctor or pharmacist before taking any cough, cold or allergy treatments whilst considering taking appetite suppressants. Some ingredients found in these remedies can lead to an increase in heart rate and blood pressure. Any cold, cough or allergy treatments should be used with caution when taken in conjunction with an appetite suppressant.

Safe weight loss remedies you can try

Rather than risk your health with unregulated and potentially harmful appetite suppressants, try other weight loss pills that have been proven to be effective and are still prescribed by doctors in the UK.

You can buy 120mg Orlistat weight loss capsules that need to be prescribed by a doctor. Alternatively, you can try the 60mg Orlistat capsules known as ‘Alli’ that you can buy over the counter.

Orlistat is not an appetite suppressant. It works in a completely different way and does not impact the brain or appetite at all. Orlistat actually binds to dietary fat and therefore must only be taken under certain conditions. You must always follow a low-fat diet plan and exercise regime when taking Orlistat.

A weight loss remedy like Orlistat is safe to take as it’s regulated and licensed — just make sure that you talk to your doctor and pharmacist so that they can safely dispense and prescribe Orlistat as a treatment and judge whether it’s suitable for you.

You can read Orlistat reviews here.

Don’t play around with your health and resort to extreme diets, unsafe diet pills, or appetite suppressants. It’s best to speak to a doctor or pharmacist if you are experiencing difficulties losing weight.

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