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Side effects of anti sickness drugs

Read about the possible side effects of anti sickness drugs. Not everyone will have side effects.

What side effects are

Side effects are unwanted or unpleasant effects of a treatment. Different drugs have different side effects. Some are very rare and only a few people will have them. By law drug companies have to list every side effect that has been reported to them, no matter how rare they are.

Your doctor or nurse should tell you about the most likely side effects of drugs before you take them. And you can ask your doctor or nurse for more information if you are worried.

Let your doctor or nurse know as soon as possible if you have any side effects. Your doctor can usually give you other medicines to help reduce the side effects. Or you could try a different type of anti sickness drug.

Serotonin blockers

These drugs block receptors in the gut and brain that send messages to the chemoreceptor trigger zone and the vomiting centre in the brain. They are also called 5HT3 blockers.

You might have the serotonin blockers are ondansetron (Zofran) and granisetron (Kytril).

The most common side effects include:

  • headaches
  • constipation

Drinking plenty of fluids, eating a high fibre diet and taking exercise can all help but you may need other medicines (laxatives) if you have constipation.

When you take serotonin blockers for chemotherapy sickness, you have them for a short period only so they are less likely to cause constipation.


Steroids can help particularly with sickness from increased pressure in your brain or a blockage in your gut. They are also used as anti sickness medicines for chemotherapy with other anti sickness drugs.

The side effects depend on the type of steroid you have, the dose and how long you take it for.

The most common steroid given for sickness from chemotherapy is dexamethasone. You usually have it before chemotherapy and for a few days afterwards.

Side effects include:

  • trouble sleeping, taking them in the morning may help
  • anxiety and fidgeting
  • flushing or tingling (when injected) but this is rare
  • pain, itching or tingling in the vagina in women or between the legs (perineum) in men (when injected quickly), this is not serious and usually lasts less than a minute
  • indigestion
  • fungal infection (thrush)

Antihistamines and sedatives

These types of drugs include cyclizine, lorazepam and haloperidol. You might feel drowsy when you are taking these drugs.

Metoclopramide and prochlorperazine

Metoclopramide (Maxolon) works by blocking the vomiting centre in your brain. It also acts directly on the wall of the gut. It encourages the stomach to empty its contents into your bowel. Prochlorperazine (Stemetil) also acts by blocking the vomiting centre in the brain.

These drugs can cause twitching in your arms, legs or face. This is rare, but more likely in children and young adults.

Stop taking the drug and let your doctor or nurse know if you notice this side effect.

Domperidone (Motilium)

Domperidone speeds up the emptying of your stomach. It also acts on a part of your brain called the chemoreceptor trigger zone. A common side effect is a dry mouth. Although rare, domperidone can cause uncontrolled movements or twitching.

This side effect is more likely to happen in children.

Let your doctor or nurse know if you get this side effect.

Aprepitant (Emend)

Aprepitant (Emend) is a newer drug which works by blocking a substance in the body called neurokinin. Some of the common side effects of aprepitant and fosaprepitant (Ivemend) include:

  • constipation
  • indigestion
  • headache
  • tiredness

Information and help

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