Side effects of drugs for diet problems | Cancer Research UK
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Side effects of drugs for diet problems

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This page tells you about the side effects of medicines used to control nutritional problems. There is information about the side effects of


Appetite stimulants

The side effects of the appetite stimulants megesterol acetate and medroxy progesterone acetate are usually very mild and many people do not have any side effects at all. But they can cause

  • Feeling and being sick
  • Headache
  • Ankle swelling from fluid retention (mild)
  • Tummy (abdominal) pain
  • Breast tenderness
  • Mood changes (rare)
  • Blood clots (this is rare)
  • Vaginal bleeding
  • Impotence in men

People who are diabetic need to monitor their blood sugar levels more closely when taking these drugs. They can cause your blood sugar levels to rise. So, you may need to adjust the dose of your diabetes medication. If you are pregnant or thinking about getting pregnant you should not take these drugs.



The most likely side effects when you first start taking steroids are

  • Difficulty sleeping, particularly if you take them late in the evening
  • Indigestion
  • High blood sugar levels, especially if you are already diabetic

Drugs for diarrhoea

Side effects of anti-diarrhoea drugs are not common, but they can happen. Tell your doctor if any of these symptoms are severe or do not go away

  • Dry mouth
  • Dizziness
  • Drowsiness
  • Feeling and being sick
  • Stomach pain, discomfort or swelling
  • Constipation
  • Tiredness (fatigue)

Drugs for constipation

Different laxatives have different side effects. Bulk forming laxatives can cause wind and swelling in the stomach (abdomen). Very rarely they can block up your bowel. So, you should drink plenty of water with these drugs to help prevent it. 

Other types of laxatives can cause stomach cramps and wind, and large doses can cause diarrhoea. The side effects usually go away once your bowels have opened. But if you continue to have cramping or abdominal swelling, or if you develop diarrhoea, let your doctor know immediately.

Remember if you come up in itchy lumps, like nettle rash, or have sudden wheezing, you could be having an allergic reaction to a drug. This is a rare but serious complication. If it happens to you, you need to go to hospital straight away.


Anti sickness drugs

There are several different types of anti sickness drugs and they have different side effects. If you get side effects, let your doctor or pharmacist know as soon as possible. You may need to change to a different type of drug. 

Some anti sickness drugs known as serotonin blockers can cause headaches and constipation, and rarely, flushing of the skin and tingling of fingers or toes. These include ondansetron (Zofran) granisetron (Kytril) and tropisetron (Navoban).

Steroids such as dexamethasone can cause

  • Trouble sleeping
  • Anxiety and fidgeting
  • Indigestion
  • Flushing of the skin
  • Tingling of the hands and feet (when injected)
  • Pain or tingling in the vagina in women or between the legs (perineum) in men (when injected into your bloodstream) - this can be a bit alarming, but is not serious and usually lasts less than a minute

Other anti sickness medicines include haloperidol, cyclizine and lorazepam. They can cause drowsiness.

Metoclopramide (Maxalon) and prochlorperazine (Stemetil) can cause twitching in your arms, legs or face. This is rare, but more likely in children and young adults.

Domperidone (Motilium) can make your mouth dry.

Further help with side effects

All prescribed drugs come with a patient information leaflet which gives details of side effects. If you think something is happening which could be caused by a drug, ask your doctor or pharmacist about it.


Find out more information

Find out about




Anti sickness drugs

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Updated: 8 April 2014