Are there interactions between PrEP and other drugs or substances (alcohol, recreational drugs)?

As a general rule, PrEP is compatible with most medications. However, there are some important interactions to be aware of.

Here is an overview of possible interactions, divided by category.

Interactions with prescription drugs

  • Hormone treatments: Whether for contraception or gender-affirming hormone therapy, studies are clear: there is no significant interaction. The effectiveness of both PrEP and your hormones is maintained.

  • Drugs affecting the kidneys (NSAIDs): This is an important point of vigilance. Frequent or high-dose use of non-steroidal anti-inflammatory drugs (ibuprofen, naproxen, etc.) can increase the risk to your kidneys, especially with PrEP formulations containing TDF (Truvada® and its generics). Occasional use is generally safe, but discuss it with us if you take them regularly.

    • Alternative: Descovy® (containing TAF) has a much lower impact on the kidneys, making this precaution less critical.

  • Certain epilepsy and tuberculosis drugs: Medications like rifampin (tuberculosis) or carbamazepine (epilepsy) can reduce the effectiveness of PrEP. A discussion with your pharmacist is essential if you are taking these treatments.

Use of alcohol and recreational drugs

There are no known direct pharmacological interactions between PrEP, alcohol, and recreational drugs. Using these substances will not cancel out the protective effect of the medication.

The main risk is behavioral: excessive use can lead to missed pills, which compromises your protection. The key is to continue taking your treatment as prescribed.

The key role of your pharmacist: safety first

For safe PrEP use, transparent communication is paramount.

Your pharmacist has an overview of all your treatments (thanks to the Quebec Health Record - DSQ) and is in the best position to detect and prevent potential drug interactions. To ensure this safety:

  1. Centralize your prescriptions at a single pharmacy.
  2. Inform us of EVERYTHING you take: over-the-counter drugs, natural health products (St. John's wort is not recommended), etc.
  3. Adhere to your medical follow-up and lab tests every three months.

This close collaboration between you, your doctor, and your pharmacist ensures maximum safety and effectiveness.

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