Several widely used medicines and supplements can alter the effectiveness or safety of antiretroviral therapy (ART), a specialist involved in HIV care has warned, underscoring the need for patients to check with clinicians or pharmacists before taking additional products.
Everyday products can change drug levels
Dominic Chow, MD, PhD, MPH, a professor at the Hawai'i Centre for AIDS and the University of Hawai'i Department of Medicine, noted that modern HIV medicines have far fewer interactions than older drugs but cautioned that interactions still occur. He stressed that even when side‑effects or interactions arise, patients must not stop or change prescribed ART without clinical advice.
“Pharmaceutical companies have done a splendid job of really creating [HIV] medications that have very little side effects and little interactions,” said Dominic Chow, MD, PhD, MPH.
The report highlights several categories of commonly used medicines and supplements that may interfere with antiretroviral drugs, particularly older formulations or specific classes of ART. These include agents that change stomach acidity, mineral supplements, certain cholesterol medicines, and some steroids.
What patients and clinicians should watch for
- Antacids, H2 blockers and proton pump inhibitors (PPIs): Drugs used for indigestion and gastro‑oesophageal reflux can reduce absorption of some antiretrovirals, notably older agents such as atazanavir and rilpivirine.
- Multivitamins and mineral supplements: Preparations containing calcium, magnesium or iron may bind to and block absorption of some integrase inhibitors, especially older integrase strand transfer inhibitors (INSTIs).
- Statins: Certain cholesterol‑lowering medicines metabolised by CYP3A enzymes can have their blood levels increased when combined with some antiretrovirals, raising the risk of muscle toxicity.
- Corticosteroids: Systemic steroids and some inhaled or nasal steroids that are metabolised by CYP3A can accumulate to dangerous levels when used with specific HIV drugs, potentially causing adrenal suppression or Cushing‑like effects.
- PDE5 inhibitors: Medicines such as sildenafil and tadalafil used for erectile dysfunction or pulmonary hypertension may reach higher concentrations when taken with certain antiretroviral agents, increasing side‑effect risk.
How interactions occur
Two principal mechanisms were explained in the reporting: altered absorption and altered metabolism. Medicines that change stomach acidity can reduce how much of an oral antiretroviral enters the bloodstream. Other drugs alter enzymes that metabolise medicines — most commonly the cytochrome P450 family, especially CYP3A — which can either raise or lower antiretroviral concentrations.
| Drug class | Potential effect on ART |
|---|---|
| Antacids / PPIs | Reduced absorption of some oral antiretrovirals |
| Mineral supplements | Binding to integrase inhibitors; reduced absorption |
| Statins (CYP3A substrates) | Increased statin levels; risk of muscle damage |
| Corticosteroids (CYP3A substrates) | Accumulation leading to adrenal insufficiency or Cushing‑like features |
Practical advice for patients in South Africa
The reporting emphasises these clear points for people living with HIV and their caregivers:
- Do not stop or alter antiretroviral treatment without consulting a clinician.
- Inform your clinic or pharmacist about all medicines you take, including over‑the‑counter products, inhalers, nasal sprays and supplements.
- Ask whether a newly prescribed medicine or supplement interacts with your ART and whether timing or dose adjustments are needed.
Modern ART regimens used in South Africa are generally safer and have fewer interactions than older drugs, but vigilance remains essential — particularly when other health conditions require additional medicines. Clinicians and pharmacists are the best sources of personalised advice; patients who suspect an adverse interaction should seek care promptly rather than self‑managing symptoms at home.
For medical concerns, consult your clinic, pharmacist or treating healthcare provider. Never stop ART without professional guidance.
