Co-trimoxazole

In Aotearoa New Zealand co-trimoxazole is available as tablets and liquid and can also be given as an injection in the hospital. 

• The dose of co-trimoxazole will be different for different people depending on the type of infection and your age.
• The usual dose for adults is 2 tablets twice a day.
• The dose for children will depend on their body weight. It's usually given 2 times a day.
• Your healthcare provider will advise you about how long to take co-trimoxazole for. It's usually taken for 5 to 7 days, but for urinary tract infections it may only be needed for 3 days.
• Always take your co-trimoxazole exactly as your healthcare provider has told you. The pharmacy label on your medicine will tell you how much to take, how often to take it and any special instructions.

Read more about the co-trimoxazole paediatric dose calculator.

• Timing: Co-trimoxazole is usually taken 2 times a day. Try to space the doses evenly throughout the day such as first thing in the morning and at bedtime. Ideally these times should be 12 hours apart. 
• Capsules: Swallow the capsules with a drink of water. Don't chew them. 
• Liquid co-trimoxazole: Shake the bottle well and use an oral syringe or measuring spoon to measure each dose.
• Food: You can take co-trimoxazole with or without food. If you get a sore tummy, take it with food.
• Missed dose: If you forget to take your dose, take it as soon as you remember. But if it's nearly time for your next dose, take the next dose at the usual time. Don’t take 2 doses at the same time to make up for a forgotten dose.
• Finish the course: It’s best to take the whole course of antibiotics for the number of days your healthcare provider has told you to. You should start to get better after you've been taking co-trimoxazole for a few days. If you don’t feel better or get more unwell, contact your healthcare provider. Don't stop taking it, even if you feel your infection has cleared up. 

Here are some things to know when you're taking co-trimoxazole. Other things may be important as well, so ask your healthcare provider what you should know about.

• Alcohol: Co-trimoxazole doesn't directly interact with alcohol. This means that most people can have the occasional drink while taking it without any serious problems. However, if co-trimoxazole makes you feel sick (nausea), don't drink alcohol as it will make you feel worse.
• Driving: Co-trimoxazole can make you feel dizzy. Be careful when driving or using tools until you know how this medicine affects you.
• Other medicines:
  • Co-trimoxazole interacts with some medicines, (eg, methotrexate, warfarin, and sulfonylurea medicines for diabetes) herbal supplements and rongoā Māori, so check with your healthcare provider before starting co-trimoxazole and before starting any new products.
  • If you're taking the contraceptive pill, you don't need to use additional contraception if you're taking co-trimoxazole. But if you have diarrhoea (runny poo) or vomiting (being sick) that lasts more than 24 hours, absorption of the contraceptive pill may be affected. If you have diarrhoea or vomiting, ask your healthcare provider for advice. 
• Pregnancy or breastfeeding: Talk to your healthcare provider if you're pregnant, planning a pregnancy or want to breastfeed.
• Vaccines: Co-trimoxazole may stop the oral typhoid vaccine from working. Have a space of 3 days between the typhoid vaccine and this antibiotic.

Like all medicines, co-trimoxazole can cause side effects, although not everyone gets them. If you're concerned about any symptoms you think might be related to your medicine, talk to your healthcare provider. The following information offers some guidance but doesn't include all possible side effects.

Common side effects

Tell your healthcare provider if these side effects bother you.

• Nausea (feeling sick), vomiting (being sick) or diarrhoea (runny poo): Tell your healthcare provider if your diarrhoea is severe, contains blood or lasts more than a few days. If you have a lot of diarrhoea or have been vomiting and you're taking the oral contraceptive pill, let your healthcare provider know.
• Small white patches in your mouth or a white furry tongue (oral thrush): Ask your healthcare provider for advice.
• Vaginal itching, soreness or discharge (vaginal thrush): Ask your healthcare provider for advice. 

Tell your healthcare provider immediately or phone Healthline free on 0800 611 116 if these occur

• Skin rash, skin peeling or blisters on the body or inside the mouth, throat or nose. This is rare and more likely in the first week of treatment. Stop taking co-trimoxazole.
• Signs of problems with your liver such as yellowing of the skin or eyes, dark urine, pain in the tummy.

Phone 111 for an ambulance or go to your nearest accident and emergency (A&E) clinic if these occur 

• Signs of an allergic reaction such as itchy skin, and rash, swollen lips or tongue, problems breathing, like a tight chest or shortness of breath.
   

Read more about medicines and side effects and reporting a reaction you think might be a side effect.