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ART Workup & Monitoring

Baseline tests, interaction pitfalls & response review

Field: Infectious DiseasesCode: ID-02BUpdated: June 2026Reference: ASHM / Liverpool HIV Drug Interactions
Check drug interactions before adding or changing anything — PPIs, antacids and some antibiotics commonly clash with ART. Viral load should fall fast and stay undetectable; flag anything off this track to the specialist early rather than waiting for the next scheduled review.

Baseline workup — before first dose

  • Viral status: HIV RNA viral load, CD4 count, resistance genotype.
  • Co-infections: hepatitis B and C serology, syphilis serology, STI screen.
  • Organ function: renal function (eGFR), liver function, fasting lipids and glucose.
  • Other baseline: full blood count, pregnancy test where relevant, vaccination status review (hepatitis A/B, pneumococcal, influenza).

Treatment response — what to expect

Viral load should fall fast and keep falling.

4wk
~1 month: viral load should have fallen substantially from baseline; if not, flag to the specialist — check adherence first.
12-16wk
~3–4 months: viral load typically undetectable; if still detectable, urgent specialist review for adherence or resistance.
24-48wk
6–12 months: sustained undetectable viral load; CD4 count recovering; routine specialist-led monitoring continues.
Stable
Long-term: undetectable viral load maintained on routine monitoring; U=U applies once undetectable for 6 months.

Key drug-interaction pitfalls

  • Rifampicin + integrase inhibitor: induces metabolism — needs specialist-guided dose adjustment, don't co-prescribe without review.
  • Proton pump inhibitors + rilpivirine: contraindicated — PPIs reduce rilpivirine absorption substantially.
  • St John's Wort: avoid with most ART — reduces drug levels via enzyme induction, risking virological failure.
  • Antacids/calcium/iron + integrase inhibitors: separate dosing by several hours — co-ingestion reduces absorption.
Interactions & U=U threshold. Check the Liverpool HIV Drug Interactions tool (hiv-druginteractions.org) before adding any new medicine. U=U (undetectable = untransmittable) applies once viral load has been undetectable for at least 6 months on stable therapy. ASHM helpline 1800 022 226 for clinician support.

Safety

  • Check the Liverpool interactions tool before adding or changing any medicine in a patient on ART — PPIs, antacids and some antibiotics commonly clash.
  • Don't co-prescribe rifampicin with an integrase inhibitor without specialist-guided dose adjustment.
  • Confirm hepatitis B status before stopping any TDF/TAF/3TC-containing regimen — abrupt cessation can flare HBV.

Red flags / refer

  • Viral load not falling as expected at the 1-month or 3–4-month checkpoints → urgent specialist review.
  • Suspected virological failure or significant side-effects on an existing regimen → specialist review.
  • Any new medicine with a possible interaction flagged by the Liverpool tool → check with the specialist before prescribing.

ID-02B v1.0 · Reviewed Jun 2026 · Review Jun 2027

For health-professional use. Framework: ASHM Antiretroviral Guidelines, Liverpool HIV Drug Interactions. Companion sheet: ID-02 ART Initiation. Doses are a guide only — confirm current dosing with the specialist.