Appendicitis typically starts with a pain in the middle of your tummy (abdomen) that may come and go.
Within hours, the pain travels to your lower right-hand side, where the appendix is usually located, and becomes constant and severe.
Pressing on this area, coughing or walking may make the pain worse.
If you have appendicitis, you may also have other symptoms, including:
If you have abdominal pain that's gradually getting worse, contact your GP or local out-of-hours service immediately.
If these options are not available, call NHS 111 for advice.
Appendicitis can easily be confused with something else, such as:
In women, symptoms similar to those of appendicitis can sometimes have a gynaecological cause, such as an ectopic pregnancy, menstrual pain or pelvic inflammatory disease (PID).
But any condition that causes constant abdominal pain requires urgent medical attention.
Call 999 to ask for an ambulance if you have pain that suddenly gets worse and spreads across your abdomen, or if your pain temporarily improves before getting worse again.
If your pain eases for a while but then gets worse, your appendix may have burst.
A burst appendix can cause peritonitis, which is a serious infection of the inner lining of the abdomen.