What to Expect After an Ozone Therapy Session

This page covers what is reported in the hours and days after an ozone session, what each route tends to cause, and the signs that mean you should get help. It is education, not medical advice. Check with your healthcare provider before starting, especially if you are pregnant, have a heart or bleeding condition, or take blood thinners. For the full list of side effects, including the rare serious ones, see ozone therapy side effects.

How will I feel after an ozone session?

It depends on the route. The Madrid Declaration on Ozone Therapy, 4th edition (ISCO3, 2025) lists the mild effects (grade 1 and 2) it has collected from published reports [1]:

• IV ozone (major autohemotherapy, MAH): itching or tingling of the lips and tongue at the end of the session, and nausea with a bad taste in the mouth while the ozonated blood goes back in. The Declaration ties these to how fast the blood is returned. A small bruise at the needle site can also happen.
• Injections: a short feeling of warmth, a mild headache, mild pain during the injection, and a bruise at the injection site.
• Rectal insufflation: belly bloating (abdominal distension) and constipation in some people.

Fatigue, headache and achiness after an IV session are also reported. MediSkill's professional guide tells practitioners to reduce the dose (by 5 to 10 gamma, the unit of ozone concentration used in IV protocols), or keep the dose and lower the frequency, after any of them. Mention them to your provider so they can adjust.

After rectal insufflation, a bowel movement or passing gas is normal. Mucus in the stool may mean the session was too strong; the professional guide says to reduce strength and volume until it stops. After ear insufflation, ears that stay wet or "weepy" usually mean too much gas, and the usual step is a break, then a restart at lower strength, time and frequency under a physician's guidance.

How long do the effects last?

Most of the mild effects in the Madrid list have no stated duration, so there is no honest single answer. What the sources do show:

• Symptoms linked to fast blood return in IV ozone (tingling in the mouth and legs, a metallic taste, pulsing temples, warmth in the cheeks, chest tightness) disappeared right away once the return was slowed, and came back when it sped up again [2].
• For Herxheimer-type reactions in general, MediSkill's Herxheimer page says symptoms usually start within a few hours to a day and resolve within 24 to 72 hours.
• Symptoms that last more than a few days, or get worse with each session, are a reason to call your provider (see below).

What have studies reported after sessions?

The counts below come from small studies and case reports, so read them as examples of what was seen, not as rates.

• IV ozone, 91 people with nerve pain after shingles: 46 people got ozone autohemotherapy (200 mL of blood with ozone at 30 µg/mL, three times a week for two weeks) plus medication, and 45 got medication alone. After treatment, the ozone group reported nausea (5 people), sleepiness (5), dizziness (4), chest tightness (4), palpitations (3) and vomiting (2). The medication-only group reported about the same numbers, and the difference between groups was not statistically significant [3].
• Speed of blood return, 11 people: all 11 reported at least one symptom (tingling in the mouth and legs, a metallic taste, pulsing temples, warmth in the cheeks, cold and tightness in the chest) during fast returns, and the symptoms disappeared immediately when the speed was slowed and reappeared when it was increased again [2].
• Healthy athletes, 8 people: three had a slight drop in performance the day after an IV ozone session. It faded after the first sessions, and the authors read it as an adaptation phase [4].
• Rectal insufflation, 20 people with a low immunoglobulin A level: two had abdominal gas distension right after insufflation and one had abdominal pain. The authors called these events mild and short [5].

What is usually fine, and when should I call?

Home methods such as ozonated oil, ozone water and sauna are not covered here because the sources we use do not describe after-effects for them. See the protocol sheets for method details.

Is a Herxheimer reaction normal after ozone therapy?

People often call a day or two of tiredness, aches or a flu-like feeling after a session a "Herx." Our Herxheimer page could not find a single published report of one caused by ozone, and says that feeling worse can also mean the dose was too high. Both need a different response, so tell your provider how you feel instead of guessing.

What do providers usually do if I feel unwell?

According to MediSkill's professional guide, the usual steps are to lower the dose or the frequency, or to stop for 4 to 7 days and restart at half the dose and time, then build back up as the practitioner directs. Physicians sometimes add vitamin C, glutathione or activated charcoal. Do not change your dose or add supplements on your own; this is a decision for your physician.

Can I exercise, shower or drink alcohol after an ozone session?

We found no source we trust that sets a rule for exercise, showering, alcohol or water intake after a session, so we are not going to invent one. Ask your provider for their instructions. The one related finding is the small athlete study above, where a slight dip in performance the day after a session eased over the first sessions [4].

When should I call my provider or get emergency help?

Call emergency services for trouble breathing, chest pain, sudden weakness, numbness, vision or speech changes, or a severe headache after a spine or epidural injection. Call your provider for fever, redness, swelling or pus at an injection site, or for symptoms that last more than a few days or get worse with each session.

Never breathe ozone gas. If you smell strong gas or cough because gas escaped, get to fresh air and call your provider. For accidental inhalation the Declaration has the provider give oxygen plus IV vitamin C [1]. See why you can't breathe ozone.

Who should not have an IV ozone session in the first place?

The Madrid Declaration lists these contraindications for systemic ozone (IV and other blood routes) [1]:

• Direct inhalation of ozone gas. The fluid lining the lungs has no antioxidants to buffer it, so inhaled ozone is toxic.
• Glucose-6-phosphate dehydrogenase (G6PD) deficiency (favism, acute hemolytic anemia). Madrid lists it as a contraindication and recommends testing, but whether it is absolute is debated. MediSkill protocols start low and go slow; see the contraindications article.
• Toxic hyperthyroidism (severe Graves' disease)
• Thrombocytopenia (platelets under 50,000) and severe coagulation disorders
• Severe cardiovascular instability
• Acute alcohol intoxication
• Recent acute myocardial infarction
• Acute massive hemorrhage
• Convulsive states
• Hemochromatosis
• Patients receiving intravenous copper or iron therapy

Pregnancy. Madrid advises avoiding ozone therapy in the first trimester (weeks 0 to 13) and reserves its use in pregnancy for specialists in gynecology and obstetrics.

Learn more

• Ozone therapy side effects: what is common, what is rare and what to watch for
• Herxheimer reactions and ozone therapy
• Safety of ozone therapy
• Major autohemotherapy (MAH) and the IV ozone protocol
• Rectal ozone therapy and the rectal protocol
• Ear insufflation protocol

Frequently asked questions

How will I feel after an ozone session?

The listed effects are mostly mild: tingling lips or nausea during IV blood return, a small bruise, some tiredness or a mild headache, or bloating after rectal insufflation. Tell your provider if anything lasts more than a few days or gets worse with each session.

Is it normal to feel tired after ozone therapy?

Fatigue, headache and achiness after an IV session are reported, and MediSkill's professional guide tells practitioners to reduce the dose or the frequency when they happen. Mention it to your provider so they can adjust.

Is a headache after ozone therapy normal?

A mild, short headache is among the mild effects the Madrid Declaration lists. A severe headache after a spine or epidural injection is not, and needs medical care right away.

Is bloating normal after rectal insufflation?

Yes, bloating and constipation are listed as mild effects, and a small study of 20 people reported brief gas distension in two of them. A bowel movement or passing gas afterward is normal. Mucus in the stool may mean the session was too strong.

Can I exercise after ozone therapy?

We found no trusted source that sets a rule, so ask your provider. In one small study of 8 athletes, three had a slight drop in performance the day after an IV session.

How long does a Herxheimer reaction last?

For Herxheimer-type reactions in general, symptoms usually resolve within 24 to 72 hours. See our Herxheimer page for how to tell one from too much ozone.

Sources

1. ISCO3. Madrid Declaration on Ozone Therapy, 4th edition (ISCO3, 2025). Sections 2.1, 2.2 and 2.5. isco3.org
2. Rimini D, et al. The speed of reinfusion affects the vascular system during ozone major autohemotherapy. Ozone Therapy. 2016;1(3).
3. The effect and safety of ozone autohemotherapy combined with pharmacological therapy in postherpetic neuralgia. J Pain Res. 2018. PMID 30214273.
4. Gjonovich A, et al. Effect of major autohaemotherapy with oxygen-ozone on the anaerobic threshold in athletes. Riv Ital Ossigeno-Ozonoterapia. 2006.
5. Systemic ozone therapy by rectal insufflation for immunoglobulin A deficiency. MEDICC Review. 2018.