Meds that cause extreme weight loss

For the past two weeks we have been considering those food-medication interactions which may cause weight gain, but there are also many medicines which suppress the appetite and cause anorexia and weight loss. I thought long and hard about including this aspect of food-drug interactions, because I did not want to impart information that can be misused in any way.

An appeal to readers

Please do not misinterpret the information in this article. It is intended for those patients who are being treated with the listed medications, who suffer from a suppressed appetite and weight loss. It is not meant for those members of the public who want or need to lose weight no matter how desperate you are. The list does include one or two medications that are used specifically for weight loss purposes, but you should under no circumstances try to obtain any of the other so-called anorexic medicines for slimming purposes. Many of these medications, such as the anticancer drugs, can cause severe side-effects and need to be taken under the supervision of a physician. Such medications are only intended to treat serious physical conditions, such as cancer or HIV or dementia, and should never be used for unintended purposes.

Anorexic medications

Appetite suppressing medications can be divided into a number of categories such as anti-infective drugs, antineoplastics, bronchodilators, cardiovascular drugs, stimulants and other medicines.

Anti-infective drugs:

  • Antibacterial - Metronidazole
  • Antifungals - Amphotericin B
  • Antimalarials - Atovaquone,  Pyrimethamine
  • Antiretrovirals - Didanosine,  Zalcitabine
  • Anti-TB - Ethionamide

(Mahan et al, 2011; MIMS, 2011)

Antineoplastic or anticancer drugs, also used to treat HIV and conditions such as psoriasis:

  • Aldesleukin and interleukin-2, Capecitabine, Carboplatin, Cytarabine, Dacarbazine, Fluorouracil, Hydroxyurea, Imatinib, Irinotecan, Methotrexate, Vinblastine sulphate, Vinorelbine tartrate

(Mahan et al, 2011; MIMS, 2011)

Bronchodilators used to treat asthma, bronchospasm, bronchitis, emphysema:

  • Salbutamol sulphate
  • Theophylline

(Mahan et al, 2011; MIMS, 2011)

Cardiovascular drugs:

  • Amiodarone, Acetazolamide, Hydralazine HCl, Quinidine

(Mahan et al, 2011; MIMS, 2011)


  • Methylphenidate HCl - used to treat Attention Deficit Hyperactivity Disorder (ADHD) or narcolepsy
  • Phentermine - used in the appetite suppressant Duromine for slimming

(Mahan et al, 2011; MIMS, 2011)

Other medications:

  • Fluoxetine - antidepressant
  • Galantamine and Rivastigmine  - used to treat dementia in conditions such as Alzheimer’s disease 
  • Sibutramine - used in slimming pills such as Ciplatrim
  • Sulphasalazine - used to treat ulcerative colitis and Crohn’s disease
  • Topiramate - anti-epileptic medication

(Mahan et al, 2011; MIMS, 2011)


While some of the above listed medications such as sibutramine and phentermine are specifically used to suppress the appetite so as to induce weight loss in overweight patients, the weight loss caused by the other drugs is usually regarded as a negative side-effect.

For example, many anticancer medicines tend to suppress the appetite and can cause a serious condition called cachexia (i.e. physical wasting with loss of muscle tissue and weight). Cancer patients undergoing chemotherapy should preferably be under the care of a registered dietician to ensure that they do not lose excessive weight or become so weak that their survival is at risk. Make sure that you consult a registered dietician to assist you during chemotherapy or treatment with antiretroviral drugs. You may need to take special liquid food supplements to boost your energy and nutrient intakes so that you do not waste away and retain your strength to fight the disease.

It is also vital that with ADHD children and adolescents who receive treatment with methylphenidate HCl (e.g. Ritalin or Concerta), are carefully monitored for weight loss and/or stunted growth. The prescribing doctor should keep a record of your child’s weight and height before and during treatment with ADHD medications. Parents can also keep such records and if your child should stop growing normally then he or she may have to stop taking  methylphenidate HCl for specific periods or completely.

Contact your doctor

If you or members of your family are using any of the above mentioned medications, except for the two slimming drugs, and you notice that you or they are starting to lose too much weight, it is important that you contact the prescribing doctor and tell him/her about this unwanted side-effect. The doctor will have to decide if the medication should or can be continued or if the patient should come off the drug for a while or permanently or if another type of medication should be substituted. Such procedures must be carried out under the supervision of your medical doctor. Don’t stop taking a medication that is suppressing your appetite without your doctor’s permission. Stopping the drug could be fatal.

- (Dr IV van Heerden, DietDoc, February 2012)


(Mahan LK et al (2011). Krause’s Food & the Nutrition Care Process. Ed. 13. Elsevier, USA; MIMS, (2011), Vol 51, No 10, October 2011.)

Any questions? Ask DietDoc

Read more:

Meds that cause weight gain
Medication that affects nutrient intake

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