How having diarrhoea can affect your medication

If you're taking a medicine and have an episode of diarrhoea, the medicine may be made less effective. This is because the diarrhoea reduces the amount of medicine absorbed into your system. While this applies to the majority of medicines, some are especially prone to reduced effectiveness during diarrhoea. These include oral contraceptives and medicines for epilepsy, amongst others.

Oral contraceptives

The effectiveness of the contraceptive pill after a bout of diarrhoea depends on the nature of your sickness and how long it lasts. If diarrhoea is accompanied by vomiting and you vomit within two hours of taking the pill, it will not have been absorbed by your body.

You can take another pill straight away, and as long as you don’t vomit again, you’re still protected against pregnancy. Be sure to take your next pill at the usual time.

If you continue to be sick or are experiencing severe diarrhoea (passing six to eight watery stools within 24 hours), this can indicate that your protection against pregnancy may be altered.

If you’re experiencing sickness or severe diarrhoea for more than 24 hours, you should continue taking your pill at the normal time, but you may need to use extra protection such as condoms.

To be safe, if you’ve been sick or have had diarrhoea for more than 24 hours, consider each day you’ve had sickness and diarrhoea symptoms as a day you missed your pill.

If you have missed a pill, your contraception may be less effective. You may need to use extra contraception such as barrier methods like condoms, and you may also need to take emergency contraception if you have recently had sex. Read the patient information leaflet that comes with your pill carefully, and consult your pharmacist or a specialist contraception clinic for advice if you're unsure.

 

Epilepsy medicine

If you have been sick or have diarrhoea, the effectiveness of your medicine could be affected. It's possible that missing a dose may lead to a seizure, but this would be rare.

Whether or not you should retake the dose of medicine depends on how soon after taking the medicine you were sick. Check the patient information leaflet that comes with your medicine for guidance, and talk to a doctor or pharmacist if you're worried or not sure what to do.

 

Other medicines affected by diarrhoea

Other medicines that may be made less effective by diarrhoea or sickness include warfarin, insulin, methotrexate, and medicines for diabetes. Be sure to consult with your Doctor or pharmacist about how these or any other medicines may be affected by illness, and what to do if you miss a dose.

 

Missed doses

• Be sure to always check the patient information leaflet that comes with your medicine for specific advice on missed doses and what to do if in event of sickness and diarrhoea

• If you're in any doubt about what to do, contact your pharmacist or Doctor for advice, especially if more than one day of treatment of any medicine has been missed.

• If you’re taking a medicine and have diarrhoea, consider whether you need to take another dose or continue with the following dose. Check the patient information leaflet, or consult your Doctor or pharmacist if you’re unsure

• If diarrhoea continues for more than seven days, consult your Doctor immediately

Next steps

 

• If you’re taking a medicine and have diarrhoea, consider whether you need to take another dose or continue with the following dose. Check the patient information leaflet, or consult your Doctor or pharmacist if you’re unsure

• If diarrhoea continues for more than seven days, consult your Doctor immediately

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