Hives after giving birth: what causes postpartum hives, relief that's safe while breastfeeding, and when a rash needs a doctor

Hives after giving birth are itchy, raised red welts that come and go, sometimes within hours. They're usually harmless and short-lived. SGH's dermatologists say the most common causes of a new bout of hives are a viral infection, about 40% of cases, and a reaction to a medicine, about 9%. After a birth that can mean the antibiotics or painkillers you were given. A pregnancy rash called PUPPP can also start right after delivery, and SingHealth says it clears within one to two months. For relief, keep cool, wear loose cotton, use calamine or an anti-itch cream, and ask about a non-drowsy antihistamine: the NHS Specialist Pharmacy Service names cetirizine and loratadine as the preferred ones while breastfeeding. Go to A&E straight away if your lips, eyes, mouth or throat swell or you struggle to breathe.

What hives look like, and how long they last

Hives, or urticaria, are itchy red bumps or welts that move around the body: one patch fades as another appears. SGH's dermatology team splits them by how long they last:

Why hives can appear after giving birth

Painkillers matter here because many new mums take them. SGH says that when chronic hives do have a trigger, it's usually NSAID painkillers or alcohol, and suggests paracetamol instead if you're prone to them. Ask your doctor before switching anything you were prescribed after the birth.

A different, rarer itch is worth knowing about. Intrahepatic cholestasis of pregnancy is a liver condition of pregnancy, and SingHealth says its main sign is itching without a rash, often on the hands and feet and worse at night. If you had it, tell your doctor if the itch hasn't gone after the birth.

Relief that's safe while breastfeeding

• Keep cool: a fan, air-conditioning, lukewarm rather than hot showers, and loose cotton clothes. NUH recommends cool baths and cotton clothing for itchy pregnancy rashes.
• Calamine lotion or an anti-itch cream on the welts, which SGH suggests for relief.
• Pat your skin dry after a shower instead of rubbing, and avoid tight waistbands and narrow bag straps.
• Keep a diary and take photos of flare-ups, so a doctor can see what the hives look like even after they've faded.
• Antihistamines: SGH's dermatologists use non-drowsy antihistamines as the first treatment. The NHS Specialist Pharmacy Service says cetirizine and loratadine are the preferred ones while breastfeeding a healthy full-term baby, and chlorphenamine if a drowsy one is needed. Singapore's medicine leaflets ask you to tell your doctor or pharmacist you're breastfeeding before you take any of them.

Drowsy antihistamines such as chlorphenamine can make you sleepy, HealthHub's leaflet warns, so don't take one before driving, and think about where your baby sleeps if you've taken one at night. Our guide to new parent sleep deprivation covers safe sleep when you're exhausted.

When to see a doctor

Your GP or polyclinic is the first stop, and the six-week postnatal check is a good time to raise hives that keep returning; our six-week check guide lists other questions. For other skin changes after the birth, see skincare for new mums, and our postnatal recovery guide has the full red-flag checklist.

Frequently asked questions

Why do I have hives after giving birth?

Common causes are a viral infection or a reaction to a medicine such as an antibiotic or painkiller, SGH's dermatologists say. A pregnancy rash called PUPPP can also start right after delivery.

How long do postpartum hives last?

Most bouts of hives settle within 6 weeks. PUPPP usually clears within one to two months of delivery, SingHealth says. See a doctor if they go on for more than 6 weeks.

What antihistamine can I take while breastfeeding?

The NHS Specialist Pharmacy Service names cetirizine and loratadine as the preferred non-drowsy antihistamines while breastfeeding. Tell your pharmacist you're breastfeeding before buying one.

Can breastfeeding cause hives?

Breastfeeding itself isn't a known cause. Hives in breastfeeding mums usually come from an infection, a medicine, heat or pressure, so look for those first.

When are hives an emergency?

When the eyes, lips, mouth or throat swell, you can't swallow or breathe easily, or you feel faint. That needs 995 or A&E, not a clinic appointment.

Is PUPPP harmful to my baby?

No. SingHealth says PUPPP isn't known to harm mother or baby, and it rarely comes back in a later pregnancy, so most mums only meet it once.