STIMULATE-ICP: repurposed drugs show small, short-term relief for long COVID fatigue

Long COVID fatigue can make everyday life feel exhausting and unpredictable. A natural question is: Could repurposed drugs reliably improve fatigue?

A phase 3 trial embedded within long COVID clinic care evaluated three repurposed regimens—colchicine, famotidine–loratadine, and rivaroxaban—using an open-label, randomized design. The overall pattern was cautious: fatigue improved over 12 weeks in all groups (including those not assigned to study drug), with only small additional signals for colchicine and famotidine–loratadine at 12 weeks, and no meaningful durability once treatment stopped.

What STIMULATE-ICP tested

STIMULATE-ICP ran within long COVID clinic models in the UK. Within that framework, investigators conducted a nested phase 3 trial with random assignment to either a study drug regimen or no study drug, while participants continued usual long COVID care.

Fatigue outcomes were assessed at 12 weeks (during the treatment period) and again at 24 weeks (after the 12-week treatment window ended).

What happened by 12 weeks (while on treatment)

Across the study, fatigue improved in all groups over 12 weeks, including the group that was not assigned to study drug—an important reminder that integrated care, time, and symptom monitoring can influence outcomes.

In comparisons that looked for an added effect beyond no study drug, the trial reported:

Colchicine: a small additional fatigue improvement signal at 12 weeks.
Famotidine–loratadine: a small additional fatigue improvement signal at 12 weeks.
Rivaroxaban: no clear statistically significant fatigue benefit.

What happened after stopping (the durability check at 24 weeks)

The most practical test was whether differences held up after treatment stopped. By the 24-week follow-up, the report indicates that fatigue differences seen at 12 weeks were not sustained. In other words, the trial’s modest 12-week signals did not translate into durable, ongoing improvement once participants were no longer taking study drugs.

Should U.S. readers self-treat long COVID fatigue with these drugs?

No—at least not based on this trial alone.

Even when a study shows a small average benefit, patients still need answers to two real-world questions:

Durability: does the benefit persist after treatment ends?
Safety/fit: is the risk–benefit profile appropriate for typical patients outside a trial?

STIMULATE-ICP’s findings address the first question negatively for most people: the 12-week differences were not sustained at 24 weeks. For the second question, rivaroxaban is a prescription anticoagulant with serious bleeding-related warnings in its prescribing information. That makes “experimenting” outside clinician oversight inappropriate.

What U.S. guidance suggests focusing on instead

In the U.S., CDC long COVID clinical guidance emphasizes symptom- and function-focused management, shared decision-making, and individualized rehabilitation/pacing strategies—especially because fatigue in long COVID can involve post-exertional malaise, where activity can worsen symptoms afterward.

Specialty guidance for occupational medicine also supports individualized fatigue evaluation and management approaches (including pacing/energy conservation and attention to overlapping conditions), rather than assuming a medication will “turn off” the syndrome.

Practical next steps for readers

Talk with a clinician about fatigue pacing and a rehabilitation-style plan. If you notice that activity reliably makes you feel worse hours to a day later, mention it—your plan may need to be adjusted to avoid trigger–recovery cycles.
Track your fatigue pattern. Keeping a simple diary of activity, symptom severity, and recovery time can help guide individualized adjustments.
If you’re considering any prescription drug for long COVID fatigue, keep the decision clinician-led. This is especially important for anticoagulants like rivaroxaban, where the labeling highlights serious bleeding risk and contraindication considerations.
Ask about clinical trials that fit your symptoms and circumstances. Public patient information resources note that long COVID has no single cure and encourage learning about trials and evidence-based options.

What remains uncertain

STIMULATE-ICP was an open-label trial nested within clinic care, and fatigue improved in everyone regardless of assignment—so expectations and the care context matter. The results also do not identify which specific subgroups might benefit more than others. The bottom line for now: the study does not establish a durable “fatigue fix” for most people with long COVID, and prescription-safety concerns mean self-treatment is not a reasonable next step.

Key sources

Editorial note: Weence articles are researched from cited public-health, medical, regulatory, journal, and reputable news sources and may be drafted with AI assistance. They are checked for source support, clarity, and safety guardrails before publication.

This article is for general informational purposes only and is not medical advice. Research findings can be early or incomplete, and health guidance can change. Always talk with a qualified healthcare professional about personal symptoms, diagnosis, medications, vaccines, screenings, or treatment decisions. If you think you may have a medical emergency, call emergency services right away.