How long does it take to see results from HBOT?

It depends entirely on the condition. Emergency conditions like CO poisoning improve within hours to days. Diabetic wounds typically need 20-40 sessions over 4-8 weeks to show meaningful improvement. Investigational uses for TBI or Long COVID typically use 40-60 session protocols, with patient-reported improvements often noted around session 20-30.

How many HBOT sessions are needed for a diabetic wound?

Most wound healing protocols run 20-40 sessions. Some wounds show measurable improvement at 20 sessions. Full protocols often reach 40-60 sessions depending on wound size, depth, and response to treatment. Medicare requires at least 30 days of standard wound care before authorizing HBOT.

Is it normal to feel worse during HBOT before feeling better?

Some patients report headache or fatigue during early sessions, especially in the first week. This typically resolves as the body adjusts. Tell your care team if symptoms are significant — they can adjust the protocol.

How soon should I start HBOT after sudden hearing loss?

The evidence strongly favors treatment within 14 days of onset for sudden sensorineural hearing loss. Improvement may be measurable within the first 10 sessions. After 14 days, outcomes are significantly worse.

How Long Does It Take for HBOT to Work?

The answer depends on why you’re getting HBOT. An emergency like carbon monoxide poisoning responds in hours. A diabetic wound takes weeks. Neurological conditions studied in research trials used 60-session protocols over two to three months.

There’s no single timeline. Here’s what the evidence shows for each category.

Emergency Conditions: Hours to Days

Carbon monoxide poisoning, decompression sickness, and arterial gas embolism are treated with HBOT as an emergency intervention. These aren’t chronic protocols — they’re acute treatments.

For CO poisoning, treatment begins immediately and typically involves 1-3 sessions. The goal is to accelerate CO elimination and reduce the risk of delayed neurological syndrome. Most patients see improvement within the first session. Follow-up sessions over 24-48 hours address residual risk.

For decompression sickness, the U.S. Navy Treatment Tables (Table 6 being the most common) structure the recompression protocol. Complete resolution may take more than one treatment, but significant symptom relief often comes within the first. Time from injury to treatment matters enormously — the sooner, the better.

Wound Healing: 4-8 Weeks, 20-40 Sessions

Diabetic foot wounds and radiation injuries follow a different logic. HBOT works here by stimulating new blood vessel growth (angiogenesis) and by delivering oxygen to tissue that’s too ischemic for normal healing. Those processes take time.

Most wound protocols run 20-40 sessions. Clinics typically assess response around session 20 using transcutaneous oxygen monitoring (TcPO2), which measures how much oxygen is actually reaching the wound bed. If tissue oxygenation is improving, the protocol continues. If there’s no response, the team re-evaluates.

Some wounds need 60 sessions. Others plateau at 30. Your wound care team will track progress at each visit.

Radiation injury to bone (osteoradionecrosis) takes longer than soft tissue wounds. Bone healing happens over months. HBOT supports the process but doesn’t speed it to weeks.

Sudden Hearing Loss: Timing Is Everything

Sudden sensorineural hearing loss is time-sensitive in a way that most HBOT indications aren’t. The evidence favors treatment within 14 days of onset. After that window, outcomes drop significantly.

Improvement may appear within the first 10 sessions. Most protocols for sudden hearing loss run 10-20 sessions, often combined with steroids. The combination of steroids plus HBOT is more effective than either alone, according to American Academy of Otolaryngology guidelines.

If you’ve had sudden hearing loss, days matter. Don’t wait for a referral to move slowly.

Osteomyelitis: Months, Adjunctive to Antibiotics

Chronic bone infections treated with HBOT typically run 20-40 sessions alongside long-course antibiotics. HBOT improves oxygen delivery to infected bone and directly kills anaerobic bacteria, but the underlying infection still requires antibiotic treatment.

You won’t see results from HBOT alone with osteomyelitis. The combination works. Bone response to any treatment takes months to confirm on imaging.

Investigational Uses: 40-60 Sessions, Weeks to Months

For off-label uses like TBI, Long COVID, and PTSD, the research protocols used 40-60 sessions. In positive trials, patient-reported improvements typically appeared around sessions 20-30, mid-protocol.

These aren’t FDA-approved uses. Insurance won’t cover them. And the timeline is real — you won’t know if you’re responding until well into the protocol.

The Efrati lab studies on TBI and cognitive function used 60 sessions at 2.0 ATA. The Gottlieb et al. (2024) PTSD trial used 60 sessions. If you’re considering a 10-session wellness package, understand that it doesn’t match any studied protocol for these conditions. (PMID: 38748905)

What “Feeling Worse Before Better” Actually Means

Some patients report headache, fatigue, or ear pressure in the first few sessions. This isn’t unusual. The pressure changes require adjustment, and some systemic inflammatory response to increased oxygenation is normal.

These early symptoms usually resolve by session 3-5. Tell your care team what you’re experiencing. They can slow the pressurization rate, adjust session length, or help with ear equalization. You shouldn’t be in significant discomfort throughout treatment.

FAQ

Can I stop HBOT once I start feeling better? Stopping early before completing the prescribed protocol is not recommended without consulting your physician. Wound healing and angiogenesis are ongoing processes. Partial protocols may not deliver the full benefit.

What if I see no improvement after 20 sessions? Talk to your hyperbaric physician. At the 20-session mark, many wound programs use TcPO2 monitoring to assess tissue response. If there’s no measurable improvement, continuing may not be appropriate. For investigational conditions, discuss realistic expectations early.

Does HBOT work faster at higher pressures? Not necessarily. Higher pressure doesn’t equal faster results for every condition. Most wound protocols use 2.4 ATA. Going higher carries increased oxygen toxicity risk without demonstrated benefit for most indications.

Medical Disclaimer: This page provides general information about HBOT timelines and is not medical advice. Treatment protocols vary by condition, clinic, and individual response. Work with a qualified hyperbaric physician to set realistic expectations for your specific situation.