1 What is Primsol?

Brand: Primsol, Proloprim, Trimpex

Generic: Trimethoprim

Primsol is a prescription-only drug used primarily to treat urinary tract infections. Primsol is ineffective in treating colds, flu, or other viral infections.

Though not mentioned on the product labels, your doctor based on his/her experience may use trimethoprim to:

  • Prevent urinary tract infections
  • Treat Pneumocystis carinii pneumonia (PCP)

Primsol is available as:

  • Tablet
  • Solution
Have a question aboutUrinary Tract Infections?Ask a doctor now

2 What to Know Before Using

Before using Primsol, you must know all about the risks and complications associated with it. Together with your doctor, you can decide whether the medication will provide you more goods than the harms.

Here are some factors to be considered before deciding to use this medicine:

  • Allergies: Inform your doctor about the allergies you have, such as to this medication, other medications, or to foods, dyes, or preservatives.
  • Pediatric: Small studies carried out among children 2 months or older, and children 12 years or older show that children and adults experience the same set of side effects.
  • Geriatric: Side effects may be more prominent in older people, and they may experience blood problems when taking this medicine with diuretics (water pills).
  • Pregnancy: Trimethoprim (oral route) falls under category C for all trimesters, meaning that due to lack of sufficient studies, it’s not clear if this medication is safe for use in pregnancy.
  • Breastfeeding: No significant negative effects to the baby are observed when used by a nursing mother.
  • Drug Interactions: Taking two medicines together can be harmful due to possible interactions. In other cases, even if there is a possible interaction between two medicines your doctor may advise you to take them together after adjusting the dose or issuing precautions. Following medicines are not recommended to be used with trimethoprim. Inform your doctor if you are using any of these medicines:

        o Dofetilide
        o Levomethadyl

Though usually not recommended, your doctor may decide, after adjusting dose or frequency of one or both medicines, to use trimethoprim with any of the following medicines:

        o Acecainide
        o Ajmaline
        o Amiloride
        o Amiodarone
        o Amisulpride
        o Amitriptyline
        o Amoxapine
        o Aprindine
        o Arsenic Trioxide
        o Astemizole
        o Azathioprine
        o Azilsartan
        o Azilsartan Medoxomil
        o Azimilide
        o Benazepril
        o Bretylium
        o Candesartan Cilexetil
        o Captopril
        o Chloral Hydrate
        o Chloroquine
        o Chlorpromazine
        o Clarithromycin
        o Desipramine
        o Dibenzepin
        o Disopyramide
        o Dolasetron
        o Doxepin
        o Droperidol
        o Eltrombopag
        o Enalapril
        o Enalaprilat
        o Enflurane
        o Eplerenone
        o Eprosartan
        o Erythromycin
        o Flecainide
        o Fluconazole
        o Fluoxetine
        o Foscarnet
        o Fosinopril
        o Gemifloxacin
        o Halofantrine
        o Haloperidol
        o Halothane
        o Imipramine
        o Leucovorin
        o Lisinopril
        o Losartan
        o Mefloquine
        o Mercaptopurine
        o Methotrexate
        o Nortriptyline
        o Octreotide
        o Olmesartan
        o Medoxomil
        o Pentamidine
        o Perindopril
        o Propafenone
        o Pyrimethamine
        o Quinapril
        o Quinidine
        o Ramipril
        o Risperidone
        o Sotalol
        o Spironolactone
        o Telithromycin
        o Triamterene
        o Trifluoperazine
        o Trimipramine
        o Valsartan
        o Vasopressin
        o Zofenopril
        o Zotepine

Rarely and only when absolutely needed, trimethoprim may be used with the following medicines even if using them together may put you at risk of certain side effects. In such cases, you may have to take the adjusted dose or change the frequency of intake.

        o Amantadine
        o Anisindione
        o Didanosine
        o Digoxin
        o Fosphenytoin
        o Phenytoin
        o Repaglinide
        o Rosiglitazone
        o Tolbutamide

  • Other Interactions: Taking your medicine together with certain foods or items such as alcohol or tobacco may cause undesirable interactions. Talk to your doctor to know if using this medicine with food, alcohol, or tobacco is safe.
  • Other Medical Problems: Certain medical conditions might influence the effects (both positive and adverse) and action of trimethoprim. DO NOT forget to inform your doctor about the following conditions:

        o Anemia: Blood problems may be more prominent if you have anemia.
        o Kidney or Liver disease: May increase occurrences of side effects.

3 Proper Usage

To use Primsol properly, you must follow all instructions given by your doctor. Here are some points to watch for:

  • Trimethoprim is not recommended for use in infants or children below 12 years while in some cases, your doctor may prescribe this medicine when absolutely required.
  • You can take trimethoprim on an empty stomach or with food.
  • Follow what your doctor says. Do not discontinue any medicine unless suggested by your doctor.
  • Take the full course of the medicine.
  • Do not skip the dose even if dosing times may seem inappropriate. For instance taking a medicine twice in a day means you have to take the medicine every 12 hours. Manage your time accordingly.


For best results, follow your doctor to know what amount of medicine you should take in a single dose. The doses of a medicine can differ according to the conditions for which it is being prescribed. If not stated otherwise, the doses here refer to an average dose. Remember your doses can differ.

The doses for the treatment of urinary tract are:

  • Adults and children 12 years and older: 100 milligrams every 12 hours for 10 days, or 200 milligrams once daily for 10 days.
  • Children up to 12 years: Your doctor will decide the dose.

Missed Dose:

Take your missed dose once you remember but avoid it if it’s time to take your next dose, and follow your normal dosing schedule. Avoid taking double doses to make up for the missed dose.


  • Store in a closed container at room temperature.
  • Keep away from heat, moisture, and direct light.
  • Do not freeze.
  • Keep away from children.
  • Discard any unused or expired medicines.

4 Precautions to Take

Before using Primsol, there are some precautions you must take. Your progress should be regularly monitored to look for some undesirable side effects or need for other interventions if symptoms worsen or persist.

  • If you develop anemia, you may take daily doses of folic acid.
  • To reduce the risk of blood problems such as increased susceptibility to infections, delayed healing, and gum bleeds, take care while using toothbrushes, dental floss, and toothpicks.
  • Schedule dental appointment only after your blood problems go away.
  • Talk to your doctor or dentist for queries about mouth care during treatment.
  • Severe sunburn or skin rash, redness, itching, or discoloration may be seen in some patients taking trimethoprim. Here is what you can do:

        o Don’t expose to sun or tanning bed.
        o Use a sun block with SPF 15 or more.
        o If you develop severe skin reactions, consult your doctor.

5 Potential Side Effects

Make sure you meet with your doctor in using Primsol to avoid unwanted potential side effects.

Consult your doctor immediately if you experience any of the following side effects:

Less common

  • Skin rash or itching


  • Tar-like stools
  • blood in urine or stools
  • Bluish discoloration of fingernails, lips, or skin
  • Breathing problems
  • Neck rigidity
  • Blistering or peeling of skin or mucous membranes
  • Swollen tongue
  • Abnormal bleeding or bruising

Mild and non-serious side effects usually go away on their own without requiring medical intervention. You may also ask your doctor to learn more about how you may prevent or reduce the side effects.

Talk to your doctor if the side effects persist or worry you, including:

The side effects of the medicine are not limited to the ones listed above. Call your doctor immediately if you experience any side effects that are uncommon or worry you. To report side effects to the FDA, contact at 1-800-FDA-1088.