Common, and usually gone within a day or twoEmerging evidence
Soreness in the area that was worked is the commonest after-effect of a massage. In 100 clients of a US massage clinic, phoned 2 to 7 days afterwards, 10% had some minor discomfort, and "The majority of negative symptoms started less than 12 hours after the massage and lasted for 36 hours or less". No one had a serious reaction.
In 25 trials of massage for back pain, more pain afterwards was the commonest side effect, in 1.5% to 25% of people, and no trial reported a serious adverse event. Across 67 trials of massage for pain, the side effects reported were soreness, pain, nausea, discomfort, sweating and low blood pressure, though only 24 of the 67 reported side effects at all. These are small numbers from one clinic and from trials that often didn't look for harms, but they point the same way.
Sources 1, 2, 3
Why firm pressure can leave you sore, and why it isn't toxinsEmerging evidence
No study has pinned down why. In two small Danish studies of people with tense, tender muscles, a muscle protein (myoglobin) leaked into the blood after massage, peaking about 3 hours after it started, and the rise shrank over repeated sessions as tension and pain eased. That points to minor stress in the muscle fibres. The studies are small and old, and neither had a comparison group, so treat this as one likely reason, not a proven one.
It isn't toxins leaving the muscles. In a lab study of 12 volunteers, massage after hard exercise slowed blood flow and the removal of lactate compared with resting, and in muscle samples from 11 young men, massage didn't change muscle lactate or glycogen. No study has measured any toxin released by massage.
Sources 4, 5, 6, 7
The back pain you went in with, and lying face downEmerging evidence
Many people book a massage because the back already hurts, and back pain has its own ups and downs. In a blinded trial of chiropractic care (another treatment, but the same question), a third of people given a sham treatment reported more pain or stiffness afterwards, so some soreness after any hands-on session would have happened anyway.
An hour face down on a massage table, with the lower back gently arched, can leave a sore back stiff, and people whose back pain is worse arching backwards often find lying flat on their front uncomfortable. No study has measured this: it is our reading, and pillows or lying on your side are the fix. Deeper work matters too: in 401 adults with chronic back pain, side effects possibly related to massage, mostly more pain, followed 9 of 131 courses of deep, structural massage and 5 of 134 courses of relaxation massage.
Sources 8, 9
Massage chairs and massage gunsEmerging evidence
No study has counted back pain after a massage chair. One case report describes a woman with no known risk factors who had sudden severe upper back pain while using an electric massage chair and a broken spine bone; osteoporosis was found afterwards. It shows this can happen, not how often.
Massage guns haven't been shown to ease muscle soreness: across 12 trials in healthy, active people there was no clear effect (very low certainty), and longer sessions, over 5 minutes per muscle, went with more soreness. In 65 active young adults, 5 minutes on one calf straight after hard exercise slightly increased soreness for 4 hours. In 38 young firefighters with chronic back pain, adding a massage gun to core exercise lowered pain by a further 0.63 points out of 10, a small difference, in a trial that reported no harms.
Sources 10, 11, 12, 13
Rare harms: bruises, broken bones in thin bones, and other case reportsEmerging evidence
Firm pressure can bruise, more easily if you take blood thinners: the NHS lists severe bruising and sudden severe back pain among the signs of excessive bleeding on anticoagulants. One man on two anticoagulants had a large bleed in his tummy wall after a handheld massager was used repeatedly on his injection site, and a person on warfarin bled into the wall of the bowel after a tummy massage.
With osteoporosis, the NHS says, "Sometimes a cough or sneeze can cause a broken rib or the partial collapse of one of the bones of the spine". A case report describes a man of 66 with osteoporosis who broke part of a lower spine bone after a back massage. Leg massage over an unrecognised clot was followed by a clot in the lungs in a pregnant woman, and the authors say massage of a leg with a deep vein thrombosis "should be contraindicated".
These are single cases. Reviews of case reports say "Massage is not entirely risk free. However, serious adverse events are probably true rarities", and found that most followed unusual techniques or massage by untrained people; in one review that counted spinal manipulation as massage, only 8 of 138 events involved massage therapists. The US National Center for Complementary and Integrative Health (NCCIH) says the risk of harm "appears to be low", with rare reports of a blood clot, nerve injury or bone fracture. Case reports can't show that a massage caused what followed, or how often it happens.
Sources 14, 15, 16, 17, 18, 19, 20, 21, 22
When it isn't the massage: the causes the warning signs cover
Back pain can have causes a massage didn't create and can't fix: cauda equina syndrome, a broken bone, infection, a burst aortic aneurysm and cancer are rare. The NHS asks for a 999 call for numbness around the genitals or bottom or new bladder or bowel changes, and a same-day check for back pain with a fever or feeling unwell. A swollen, throbbing calf can be a deep vein thrombosis, which needs a same-day check, and sudden breathlessness or chest pain can be a clot in the lungs. A broken rib with breathlessness or tummy pain needs 999, the NHS says.
From 50, past the menopause or on long-term steroid tablets, sudden back pain after little force can be a spinal fracture from thin bones: NICE's osteoporosis guideline covers finding these fractures, and an NHS trust says that very occasionally a piece of broken bone presses on the nerves, so new leg weakness needs to be seen urgently. The warning lines on these come from single case reports, as our sports massage page sets out: a kidney injury after a deep tissue massage for back pain from an unlicensed therapist, a pancreas injury after a tummy massage, and a nerve injury in the forearm after massage, so severe tummy, side or back pain after a massage, or numbness that lasts, needs checking. Dark pee with severe muscle pain after heavy massage gun use can be a breakdown of muscle, from a single case report.
Sources 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35
When a scan helpsStrong evidence
Not for soreness after a massage. NICE says "Do not routinely offer imaging in a non-specialist setting" for low back pain, and in people with no back pain at all, disc wear on scans rose from 37% at 20 to 96% at 80, so a scan finding rarely explains new pain. Tests matter for the warning signs: an X-ray, and a bone density scan, for a suspected broken spine bone or rib in thin bones, an emergency magnetic resonance imaging (MRI) scan for suspected cauda equina syndrome, and an ultrasound scan for a suspected leg clot, which the NHS says you should be referred to hospital for within 24 hours.
Sources 36, 37, 25
How it usually goesStrong evidence
Most massage soreness starts within 12 hours and is gone within 36. If the massage flared back pain you already had, new back pain improves most in the first 6 weeks: in 33 groups of 11,166 people, average pain fell from 52 out of 100 to 23 by 6 weeks and 6 by a year, and NHS inform says most back problems should have improved within 6 weeks. No one can promise a date.
Sources 1, 38, 24
