Trimethoprim is an antibiotic commonly used to treat certain infections like Cystitis. Some doctors also recommend trimethoprim for chest infections and acne. In this blog post, you will learn about the proper way to take trimethoprim as well as the common side effects of trimethoprim tablets.

How And When To Take Trimethoprim Tablets

Trimethoprim is usually taken two times a day - once in the morning and once in the evening. This treatment doesn’t upset your stomach so you can take it without food.

The usual dose of trimethoprim tablets depends on the type of infection being treated, your age and any other underlying conditions. Elderly people and those with damaged kidneys are usually given lower doses.

Purpose Common Dose
To treat UTIs 200 mg tablets twice a day. You GP may advise you to double the first dosage (400 mg).
Treating cystitis that comes after sex A one-off dose of 100mg. Taken within 2 hours of having sex.
Treat acne 300 mg twice a day. Your doctor may reduce this dose over time.
Preventing infections 100 mg once a day. Take at bedtime.

You take trimethoprim by swallowing the tablets whole. If you find it hard to swallow tablets, trimethoprim is also available in made to order liquid form.

Always follow the dosage given by your doctor to avoid trimethoprim side effects.

How Long Is A Trimethoprim Course?

Again, the length of your antibiotic course will depend on your age, sex, underlying health problems, and infection being treated.

Women with UTIs usually take trimethoprim in a 3-day course. Men and pregnant women, on the other hand, need to take the antibiotic for 14 days. If you have a catheter or a complicated form of UTI, the common length of treatment is also 14 days.

If the UTI developed a complication called prostatitis or swelling of the prostate gland (men only), you may need to take a trimethoprim course of 4 to 6 weeks.

If you forget to take a dose, take it as soon as you remember. If it’s close to your next dose, skip the missed tablet and continue as normal. Never double dose unless directed by your doctor.

Common Side Effects of Trimethoprim Tablets

Most people taking trimethoprim experience mild itching or skin rash. This side effect usually goes away on its own after you stop taking the medication. The other common side effects of trimethoprim include:

  • Diarrhoea
  • Headaches
  • Feeling sick
  • Loss of appetite
  • Taste problems
  • Vomiting
  • Nausea

Although rare, serious trimethoprim side effects can also happen. Stop taking the antibiotic and call your doctor immediately if you experience:

  • Abnormal heartbeat, muscle weakness, and chest pains (you may have high potassium in your blood)
  • Serious skin rashes, swelling of the skin that looks like burns, skin ulcers, blisters
  • Headaches accompanied by fever, stiff neck, sensitivity to bright light, or tiredness (these can be symptoms of meningitis)
  • Severe diarrhoea that lasts for more than 4 days or diarrhoea with blood
  • Unexplained bruising or bleeding
  • Sore throat, mouth ulcers or fever

Serious allergic reactions to trimethoprim are also possible. Get immediate medical care if you experience:

  • Wheezing
  • Skin rash with peeling or blistered skin
  • Trouble breathing or talking
  • Swelling face, mouth, lips, throat, or tongue
  • Feeling of tightness in the chest

The best way to avoid these trimethoprim side effects is to always follow the dosage as directed by your doctor.