We use cortisone injections for arthritis and tendonitis, and one of the most common questions is how long it takes for a cortisone shot to work. This page answers that directly, then covers the other questions people ask before and after a cortisone injection.

How long does it take for a cortisone shot to work?

Generally, a cortisone shot takes about 1–2 weeks to start working. If you have an event coming up — a marathon or a sports final — we usually suggest having the shot at least a week beforehand, so the timing works in your favour.

It’s important to know that cortisone can cause a flare of pain in the first few days before it helps (more on that below), so you should rest for a few days after the shot. The maximum effect builds over about 2–4 weeks — so if it hasn’t worked immediately, don’t give up; we usually wait a full 4–6 weeks before judging whether a shot has worked.

(For how long the relief then lasts, see our dedicated page on how long a cortisone shot lasts.)

Why does a cortisone shot work?

Cortisone is a corticosteroid — a drug that reduces inflammation. Joint and tendon problems cause inflammation, which leads to pain and limits activity. A cortisone shot dampens that inflammation. The effect is temporary: cortisone doesn’t cure arthritis or tendonitis, but the pain-relief window makes rehab more effective.

Do cortisone shots hurt?

ultrasound-guided wrist injection

Usually, there’s some discomfort, but with a local anaesthetic, most people tolerate it well. Ultrasound guidance helps direct the cortisone precisely, reducing discomfort and improving results.

Tell your doctor your medical history

Cortisone shots are very safe, but some conditions — diabetes, cancer, or HIV — can interact with cortisone, so tell your doctor. (We cover cortisone and diabetes in detail separately.) Modern evidence suggests you generally don’t need to stop a blood thinner such as warfarin for a joint injection, but always check with your doctor.

Why might a cortisone shot not work?

A shot can fail for a few reasons: the wrong diagnosis, the wrong injection site, or poor needle placement (which is why ultrasound guidance matters), and failure to follow up with proper rehab.

The cortisone flare: pain after a cortisone injection

The commonest side effect is a cortisone flare — increased pain in the first few days. A flare usually starts after about 6 hours and lasts up to 5 days (one study found an average of about 4 days). If it happens, rest from aggravating activities, ice the area for about 10 minutes every few hours, and take ibuprofen 400mg up to three times a day. Ibuprofen and other anti-inflammatories help settle a flare.

(For more on rest and recovery afterwards, see Do You Need to Rest After a Cortisone Injection?)

What are the side effects of a cortisone shot?

Cortisone shots are generally very safe, but possible side effects include a rare allergic reaction, infection (around 1 in 100,000), temporary skin thinning or discolouration (reduced with ultrasound), bleeding into a joint, a temporary rise in blood sugar in people with diabetes, and the cortisone flare. There are also concerns about repeated injections — frequent cortisone can weaken tendons or harm cartilage, which is why we use cortisone sparingly. We cover the risks in full on our page. Are corticosteroid injections bad for you? page.

How many cortisone shots can you have?

There’s no strict limit, but there are concerns about repeated injections in the same area. If a first shot doesn’t work, we may repeat it after 6–8 weeks; if a second doesn’t work, we don’t recommend a third in the same spot.

Can you have two cortisone shots at once?

Yes, but cautiously. Because a shot can cause a flare, we avoid injecting both sides (both knees or hips) at once — doing one side at a time, a week apart, means you can still function if one flares. Two shots together also means a bigger cortisone dose, which can cause side effects such as tiredness in older patients.

Frequently asked questions about a cortisone shot

Can you drive home after a cortisone injection?

Wait at least 15 minutes (a shot can briefly make you lightheaded). For hip, knee, or foot injections, or a shoulder/elbow/hand injection that limits your control, we advise not driving yourself — arrange a lift, taxi, or public transport.

Is a cortisone shot safe in pregnancy or breastfeeding?

Cortisone is generally considered safe, but we avoid it in pregnancy unless necessary and suggest speaking to your obstetrician — see cortisone shots while pregnant. Breastfeeding is fine: only a tiny amount reaches breast milk.

Can cortisone shots affect your periods?

Yes — more often than people expect. A study found that a steroid injection disturbed the menstrual cycle in just over half of women (heavier or lighter bleeding), usually for one cycle only. Women on the contraceptive pill had less variability.

Do cortisone shots cause weight gain?

Generally, no weight gain is associated with high-dose cortisone tablets over weeks, not with one or two injections. See whether cortisone shots cause weight gain?

Can a cortisone shot cause hiccups, flushing, or insomnia?

Yes, all are recognised but uncommon, and short-lived (1–2 days). Facial flushing is more common in women, especially with triamcinolone, and settles on its own (an antihistamine helps).

Can you get a cortisone injection after a joint replacement?

We generally advise against injecting a replaced joint because of the infection risk.

Do cortisone injections damage joints?

One study found frequent injections harmed knee cartilage — but those patients had eight injections over two years. One or two injections are safe and effective; the concern is repeated injections into one joint. More on this: Are cortisone injections bad for you? page.

Can you have a cortisone injection on blood thinners?

Probably yes. A study showed bleeding wasn’t increased regardless of blood-thinner dose, so you usually don’t need to stop or reduce it for a joint injection — but check with your doctor.

Are cortisone shots better under ultrasound?

Yes — good evidence shows ultrasound guidance improves accuracy and effect. See a doctor experienced in ultrasound-guided injections.

Can a cortisone shot help bursitis?

Yes. Bursitis often follows tendonitis (for example, trochanteric bursitis from hip tendonitis). Cortisone helps with the pain, but it should be combined with physiotherapy.

What happens if a cortisone shot hits a nerve?

It causes brief burning, pins and needles, or numbness, usually settling within minutes. If the nerve is bruised, symptoms can last days to weeks but generally recover.

Do cortisone shots make you tired?

One injection is unlikely to. Two or three at once can briefly suppress the body’s own cortisol production, causing fatigue, especially with the more potent triamcinolone.

Are there alternatives to cortisone?

Platelet-rich plasma injections - alternative to cortisone injection in shoulder

Yes. Hyaluronic acid (such as Durolane) often provides longer-lasting relief in arthritis; PRP provides long-term relief for knee arthritis and some tendonsCombining HA and PRP may be better still, and Arthrosamid is promising for knee arthritis. We compare the two main options directly on cortisone vs hyaluronic acid.

Final word from Sport Doctor London about how long a cortisone shot takes to work

A cortisone shot is a safe, effective procedure for many musculoskeletal conditions, but it matters who does it. It usually takes about a week to start working, with the full effect by 2–4 weeks. See a medical doctor experienced in ultrasound-guided injections.

To book a cortisone injection with Dr Masci in London, contact the team here or view the injection fees.

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